A look at Staff Combat.

[Chronosplit]

Staves are used for a variety of reasons in melee. The problem is that the tree is mostly a "rush to the mastery talent and you're done" deal. This is because:

A. For those who want to use them in melee (AB etc.) you're stuck with a staff without mastery for a little while unless you get lucky and find an Alchemist escort (or use addons to choose one as your first escort). The reason for this is that even if you rush out to the tree quick as possible, Staff Mastery is second in the tree after a talent these types of classes are unlikely to use (Why use a 5/5 110% Channel Staff instead of a 120% Rush of any level?) In comparison, Weapon/Dagger Mastery is almost always right there for you to have and you'll most likely have the stats for 1 point of it before Staff Mastery. Sometimes you start with a point in it already.

B. For mages themselves there is very little use in the tree. Channel Staff, even at a 5/5, is rarely worth it outside of things like being a source of Corona crits. You usually don't want to be in range where your other staff skills come into play, and the last two talents in the tree aren't worth the digging at all for some extra armor and a stun attack that'll always hit with heavy investment. In comparison, Psiblades are awesome for most classes that always use mindstars.

So, how do we fix this one? I've thought up a few ideas which may or may not be good.

1. Mastery talent should be the first talent in the tree, like Psiblades. Maybe put something in that more ranged classes can use (spellpower perhaps), maybe just make it a point tax for them.
2. Channel Staff could possibly be shuffled in to the second slot, but buffed in damage. An idea to make it at least a 1 point wonder is to give it an effect that depends on what element you have attuned your staff to (enemies can be Blinded with Light, Flash Freeze with Cold, etc.).
3. While Defensive Posture is a nice idea in theory for something likely to not have the best in armor, it isn't worth the points especially when it costs mana. An idea would be to take inspiration from Chants and raise Armor Hardness, or even provide protection from enemies a certain amount of spaces away.
4. Blunt Thrust should either be moved somewhere else in the tree or given a massive buff, as it is it isn't worth much at all. A cooldown reduction to make it able to work like Stunning Blow or Dual Attack, perhaps? It's still debatable if it's worth the dig even then. Another alternative is to replace it with another talent (something like current Bulwark's Repulsion may actually have some merit, swinging your staff around or something).

[St_ranger_er]

(Why use a 5/5 110% Channel Staff instead of a 120% Rush of any level?)

Did you saw that one line

This attack always has a 100% chance to hit, and ignores the target's Armour.

?

[ghostbuster]

(Why use a 5/5 110% Channel Staff instead of a 120% Rush of any level?)

Did you saw that one line

This attack always has a 100% chance to hit, and ignores the target's Armour.

?

Also, channel staff deals the staff damage type, that is increased by 10-30% depending on the tier of the staff.
And it has a zero cooldown and a low mana cost. If given additional effects, this should be changed.

BTW, the arcanum addon by HousePet changes staff combat in a way similar to your proposal (in two trees).

[HousePet]

TBH I'm considering condensing the Staff categories in Arcanum. They are still pretty weak compared to Mindstar Mastery.

[astreoth]

staff combats biggest problem is it was built for alchemist back when they were trying to make it a dex based warrior mage class.

tree was built to be both a caster and melee tree but was never very good at either the only reason a mage would want it is so they can channel staff at enemies when their spells are on cooldown.

and the only reason a warrior would want it is if their a melee/caster combo who wants the element damage boost of a staff but doesn't want to completely give up on melee damage.

there are few classes with these problems the wants of the two groups don't intersect much so they will always despise the half of the tree that doesn't cater to their wants and staff combat is just a really weak tree to begin with.

fixing the tree would require a revaluation of what the tree is supposed to be and I see three ways that could go

1. like alchemist did we dump the melee section of the tree and make it a booster for staffs and then buff what remains

2. do what housepet did and split the tree into seperate caster and melee trees

3. we try to make the tree work for both groups by giving it talents that both would like

my suggestion for doing #3 would be

staff manipulation
for the first talent we merge staff mastery and channel staff both talents are weak on there own and both the melee and caster factions will hate the other for not putting there talent first
in addition at talent level three the you get a spell from this talent depending on the channeled element with some kind of support effect useful to the classes that use that element like light being used by celestials who all have the light tree could have an aoe pulse that lights up the area, blinds, applies a light dot, but doesn't do those last two to anyone with a shield instead restoring a percentage of the max shield strength.
overall this talent would keep melee happy by giving them a way to get the high damage scaling of melee at a distance in elements that ignore armour and benefit from the staff damage boost
and keep casters happy by letting them channel staff early on before they get a good spell rotation and gives them a reason not to just float the talent points out later on by giving them a useful support ability.

threaded channeling
this talent will allow you to channel a second element through your staff at a tier equal to the talent level but no higher than the tier of your equipped staff as well as giving the staff damage conversion equal to how much of a boost you get to the element.
whether caster or melee if you use a staff you rarely do damage in just one element.
the melee will also get added value from the element their stacking getting added to their melee attacks as well as being able to boost their phys damage at the same time.
plus casters will get access to another support spell from staff manipulation maybe a third behind a breakpoint.

mana recycle
sustain that gives mana regen for non-mana using classes who decided to take this tree
as well as a chance to proc short term benefits on melee or spell hit, cast and or crit with the bonuses depending on channeled elements.
since most of the melee who might want to use staffs have some form of hitting enemies with spells on melee hits this is mostly here to be a defensive counterpart to arcane combat.
for casters it mostly gives a way to access the benefits of this tree without having the class specific quirks staff manipulation will be built around like the light example from earlier this could give a shield that the light example could boost.

wielded through magic
sustain
your mastery of channeling magic through staffs has reached the point where you lift it more through magic than actually strength.
your staffs newfound weightlessness allows you to wield it one handed giving you new options in equipment

pure staff + spell cooldown reduction, + spellpower, +fatigue reduction
gem offhand attune a gem to your staff giving you the gems benefits as well as channeling the gems element at its tier effectiveness giving access to another staff manipulation spell
weapon mainhand staff offhand you get to hit them with a sword and staff reduced damage from staff
dagger offhand you infuse the knife with magic giving it damage conversion Ala threaded channeling as well as lifesteal on hit

yeah the capstone is where this tree finally directly improves your magicing casters who just want to improve there ability to cast spells can just take a staff alone those who actually like the rest of the tree can make it better with a gem and melee get access to giving up staff damage for a weapon or a magically augmented weapon

there something for everyone except the guy who codes all that.

[HousePet]

For something a bit easier to code and fit into the talent descriptions, I'd probably go for something like:

Staff Training:
Passive+
Works as the mastery talent for weapon damage and physical power.
Also grants the Channel Staff active. (Possibly just make Channel Staff a 1 point talent which does 100% weapon damage, as otherwise its an odd double dip in scaling.)

Blunt Thrust:
Active.
Similar to existing Blunt Thrust, but projects physical damage with stun in a short beam with range dependent on talent level.
Damage scales with Willpower.

Defensive Stance:
Sustain.
Same as current, but also increases Spell Save.
Still scales with Dexterity.

Staff Arcana:
Passive+ (might need to be sustain for technical reasons)
Increases Channel Staff multiplier, mana regen, and the Spellpower and Spell Crit values on your staff.
Also grants the Invoke Staff talent, which does a mass damage+debuff effect dependent on staff element.

[Razakai]

Agree that merging mastery/channel into the first talent makes sense, with channel just being a straight 100% damage as staff element bolt. Staff Arcana as a variation on how Psiblades increases stats also works.