I learned a lot from my winning run through in beta 18 with Hiruma Kai, who was also an arcane blade, and was able to do more of the quests leading up to the end game. My original commentary on that character is in this thread.
Talents
1) This time around I decided to focus more on the martial talents. So I planned on grabbing Rush, Blinding Speed, and Blood Frenzy (mostly for the Limmir quest).
1a) I used rush quite a bit. The cooldown reduction is nice, plus combined with the "of the Dragon" armor brings it down to a very respectable 13 round cooldown.
1b)Blinding speed also got used on boss fights and whenever I was in a pinch (say particularly bad orc ambushes and the Limmir Quest). Having it not cost me a turn made it a "sure, why not."
1c) Blood Frenzy unfortunately was only useful on the Limmir quest (where it was *extremely* helpful) and when I intentionally grabbed a large crowd in some of the Orc pride bases. Otherwise it just wasn't worth it. Its really only useful in endurance type fights with many, many enemies. Not sure if it was a good investment or not. Certainly not useful in the end fight, which was the place which eventually killed the character.
2) These martial talents meant the character needed alot more stamina recovery, so I grabbed the Combat Techniques tree containing Quick Recovery and Unending Frenzy.
3) Traditionally I'd grab 2 extra rune/infusion slots, along with Conveyance and Divination. This time I skipped Divination (partly because I got 2 talents from the lost seer).
4) Perhaps I should have put some extra points into Displacement Shield and actually tried using it, but the cooldown always put me off, the amount of damage done was less than an auto attack, and up until the last fight, I wasn't having hit point problems.
Quests:
Crypt and Melinda: I actually braved the crypt because it didn't pop until level 26 for him. Getting down wasn't too bad, but I wasn't able to save the girl. Even with phase door and a rush, I was about 8-10 turns to slow. And I was a high damage Arcane blade wielding a Voratun Greatmaul and using Arcane Combat tossing out Flames. Right now that quest favors high damage ranged strikers and casters a lot.
Given the changes in AI and the distances involved, I think the timer needs to be extended by at least 10 turns. Of course, since rogue-likes don't necessarily need to balanced, it can just favor the archers and casters. One suggestion is to perhaps add a destroyable altar (ala a non-moving, non-attacking mold like thing) with high hitpoints/resistance. A fighter/low-damage type can run up to it and smash it since it doesn't move, while relying on their survivability to take fire from 4 acolytes at once. Timer stops once the altar is destroyed, but girl still isn't freed until all 4 p's go down.
The Run in the Charred Scar: So I went into this wearing boots of speed and a staff of chronomancy which added -20% and -10% to movement together. This seemed to be sufficient to get me through with nearly 200 turns to spare. I don't know if was just luck on how things spawned, the 4 moves to everyone else's 3, or if the quest had been changed, but it was much easier than the last time. Given I barely used any ability or attacked anyone, I think the quest is fine as is. Any class should be able to slap on some fire resistance with boots of speed/movement staff.
Limmir and the Valley of the Moon: This is where blood frenzy and unending frenzy were really used. I played around with those abilities in some of the Orc Pride bases, but they really only showed their stuff on that mission. I'm still not sure if it was worth the investment for that one fight. But I do admit they were thing that made that mission possible.
At the end Limmir only had about 30% health, and I was barely keeping up by using auto-attacks. Although I admit it was fun having a listed damage of 1070 and killing big U's in a single swing. I wouldn't mind another "endurance" type fight against many small enemies. It made my Arcane Blade feel kinda like a cursed, constantly trying to find the next enemy to hit to keep increasing damage.
As a side note unenchanted Voratun rings have to be the rarest thing in the game as far as I can tell. I only found 2 during the game normally as drops, one being in High Peak. The other 2 I effectively had to visit Angolwen repeatedly to eventually get. I saw far more artifact rings than I did those.
The Final Fight
I went in expecting it to be similar to my previous winner's fight, but several changes made all the difference in the world (literally in this case.

1) First off was the change to no teleportation/probability travel. This fact only dawned on me half way through the fight. Back in beta 18, I remember being able to teleport, phase door, and probability travel. I kept looking for error messages or something to tell me I'm not allowed to teleport (trying Phase door about 4 times), but there were no messages indicating why they were failing. I kept thinking some wierd curse or effect must be on somewhere. I turned probability travel on and when I couldn't walk through walls, I realized what was going on.
Strategically, this means people with controlled phase door runes should swap them for shields or healing just prior to entering the final level, since they're non-functional. Given how I'd been abusing probability travel to get to the end game, I can understand why its disabled.
2) I'm not sure if this is a bug, but as far as I could tell Argoniel was completely immune to physical damage. He only lists 50% physical resist (along with 50% resist all). This I feel might be a bit extreme. As an Arcane blade, I at least have access to some fire and lightning, but thinking of a fighter or berserker I'm not sure how they would deal with him. Unless he becomes vulnerable after time or after the other boss goes down? Or is it some really high armor and I need to push APR?
3) Similarly I was only doing 150 to maybe 200 physical damage a turn to Elandar. I vaguely remember doing about twice as much on my previous run, so I realized I may need to actually shut the portals. I started on that task a bit to late, and the several aborted PD attempts didn't help, so I was getting some undead and dragons at the end. I figure now it'd take about 40-50 turns to take Elandar down, assuming he didn't use a healing infusion (although according to Std Out he had one) so its probably would have taken more like 80-100.
4) Apparently the 725 and 625 regen infusions on 15 and 13 cooldowns, plus the 600-ish Shield every 16 were not enough healing. Even with 55% increased healing. The fact that healing infusions cooldown in the 10's now, along with the Infusion suppression definitely makes characters less survivable. I also was constantly being hit with curses/hexes, such that the 1 wild infusion didn't seem like enough, only removing 1 random one every 13 turns or so. Even before extra enemies started showing up I had already died once. The constant state of curses + acid (dropping my armor to 1 or so) were rough.
5)Pinning was a serious problem and I probably should have grabbed some resistance to it, especially since my normal methods of dealing with it did not work at all (namely teleport, phase door and probability travel). Also getting battle called (I assume thats what was moving me around) and pinned next to the virtually immune Argoniel was very effective for the sorcerers.
So at the moment I'm not sure how to re-approach the last fight, if I were to make another run at it with an Arcane blade. If Argoniel has a healing type infusion, he'll be effectively impossible to kill. I'd definitely want to get at least some pinning resistance.
However, that still doesn't change the fact I was doing to little damage and taking too much. My usual survivability was thrown completely out (i.e. break LOS).
What to do different next time for the last fight - taking stock:
Arcane blades have the advantages of high damage, high mobility, and stuns. Unfortunately, the final fight removes those advantages through high hit point/high resistance enemies and simply outright denying the use of most of the mobility talents. You can't burn your opponents down before you go down or disable them so you must have sustainable hit points, and you can't use breaking LOS to buy yourself a breather.
Movement/Knockback: An arcane blade's only valid positional talent in the final fight is Rush (which I had at 5/5), which while useful for getting to the enemy fast, doesn't help them survive. Arcane blades have no way to knock opponents away, for example. The speed disadvantage against the Essence of Speed Elandar doesn't help either. You also need pinning resistance (getting pinned for 7 turns is pretty much a death sentence).
Disabling: You can't use Stunning Blow or Flameshock to stun either boss (or at least I didn't see any stun messages on the info message when you hover the mouse over the bosses).
Health/Shield/Defense: I had pretty much maxed the armor and health talents (and even had duplication since I didn't know what end armor I might find). I also had maxed my infusion/rune slots. 1 Wild, 2 Regeneration (~750 hp/15 turns and ~650/13 turns) and 1 Shield (~600 every 16 turns). The last was a manasurge which is basically needed for sustained engagements using mana. However those clearly were insufficient for the job.
The only additional shield talents are Premonition and Displacement shield. I was running Premonition when I came in, although that only maxes me against 1 damage type resistance wise (and is excess when the Wild infusion is up). I'm not sure Displacement shield does enough to justify its 80 mana cost and 35-ish turn cooldown. I think tool tips indicated 300-400ish hit points at 5/5 when I was looking around. Even at 525 hit points over 35 turns, it still roughly 1/5th as effective as one of my Regen infusions when averaged over cooldowns. So sustainability wise its less than a 10% improvement, which I don't think is enough to make the difference.
Damage Output: Not really sure what I could change here. Perhaps go for a more crit focused build with different equipment and Precise strikes? Drop Blood Frenzy and grab Sunder Armor to 5/5 to help against armor? The gear I had I thought was pretty much top of the line so I'm not sure if I could eek out all that much more. Not to mention it'd take alot of grinding to find much better offensive gear I think. Also I need some way of dealing with Argoniel efficiently. Flaming once every 6 turns for 250 damage pre-resistance is going to take awhile.