I understand the point of the initial 2 melee classes being that they are simple to use and understand, but the move set offered to low level Berserkers is as generic and uninteresting as they can get.
So how do you spice it up without adding a new resource type? Put greater emphasis on the risk / reward meta-game of fighting at lower-than-maximum life points.
As it stands, the only ability that interacts with your current life points in this manner is Vitality, and that is just a generic talent, not a class specific one (Bulwark also has access to it). It also doesn't scale really, it just waits until you are at 50% hp to activate.
I have a fairly easy to implement (I hope) set of changes that would go a LONG way towards making the class more flavorful from the beginning, and address the lack of interesting unique mechanics.
- Replace Two-handed maiming with Bloodthirst
A pair of 2H talent sets instead of a pair of Shield talent sets is the main difference between Berserkers and Bulwarks right now. Bloodthirst is the most interesting, useful, and flavorful talent set unique to Berserkers and as such should be given immediate access. Two-handed maiming is not really interesting because the Sunder skills are not interesting and they make up half the set. - Exchange the positions of Mortal Terror and Bloodbath
Bloodbath relies on critical hits to actually do anything, so why is it you get access to that before the talent that gives you +3% critical hit chance per point? - Bloodrage
Instead of a passive that triggers on enemy deaths, change this into passive that gives you a Strength bonus which scales with your current life. At full life, no bonus, but for each missing % of life, you gain that % (base) Strength bonus. The scaling would need worked out, but the general idea is sound. This would create a lot of interesting situations and really add a lot of flavor to the class, allowing for narrow victories and a unique interaction with the Adrenaline Surge talent (lets you spend HP when Stamina runs out to fuel abilities) which Bulwarks will not be able to duplicate. - Berserker
For your namesake ability, it really isn't that interesting. Just a passive set of stat tweaks, with a penalty that is only really worth worrying about in the early game. That is a problem, if you ask me, because why wouldn't a Berserker be able to go Berserk from the start of the game? So, swap it with Death Dance so you have your namesake ability from the get-go. Next, make it less punishing for low level players! The concept as it stands seems to be, you are fighting recklessly with an emphasis on smashing your foes. From a flavor standpoint, that indicates to me there is no reason to lower your armor rating, but also no reason to raise your accuracy. You are smashing wildly, not running around naked! So, what if it just raised your power and lowered your defense rating? That way low level players could enjoy Berserking without giving up their armor rating. They would get hit more often, but the damage would be more consistently managed by armor. Throughout the rest of the game keeping this 10 armor will allow players to fine-tune their risk taking strategy in conjunction with the redesigned Bloodrage as damage will be less spikey in general.
For initial testing I would literally just remove the armor penalty and accuracy bonus, and see how that went. It would not really be interesting yet, though. Part of me thinks Berserking shouldn't be something someone can do non-stop, it should be tiring, but shouldn't just run out in the middle of a battle. To make Berserking more interesting as a mechanic it would be nice if once activated, there was a turn limit. This turn limit would not be static, though. It would increase every time the player took damage, proportional to the damage received ideally. So for example, getting hit for 1%-10% of your max life would add 1 more round to the duration, 11-25% would add 2 rounds, 26-50% would add 3 rounds, and getting walloped for half your life or more in a single attack would add 5 rounds. To compensate for this new limitation, an increase in power! While Berserking the player would gain 5% move speed and 5% attack speed per talent rank in addition to the previous increased power bonus. Once Berserker ran out, though, it would be on cooldown for 22-19-16-13-10 turns based on talent rank, with 10 turns at 5/5.

That is all for now!
I really love ToME and especially the Alchemist class. It really raised the bar for my expectations of what classes in ToME are capable of in terms of flavor and interesting mechanics, so I hope to be able to implement these alterations to Berserker.
What do you think? Berserker fine like it is? Maybe I'm missing something special about it? Or, you like my ideas?