Guild Wars 2

I have a Thieves Guild site that I’m constantly trying to add information to that would help members acquire a better understanding of the class.
Recently I added a section on stat functions to help people decide which stats to choose for their build and in what proportions.
Considering that, due to a lack of public information on certain areas, I was forced to due a fair amount of math on my own, I likely made some mistakes here and there.
I also won’t claim to be some great master of the class, and may have overlooked some gameplay elements that would change the conclusions I’ve made.
And so I was really hoping to get some second opinions on it to clear out any mistakes I may have made.

Here’s the post:

Here I’ll go into detail on how the character stats work relative to each other, so you can decide how best to stack them for your build.

Offense
Power, Precision, Condition Damage, and Critical Damage.
Power adds raw damage to non-condition attacks, and Precision increases your chance of a critical strike.
By my math, in terms of raw damage output Precision is roughly 17% less effective per point than Power, without any points in Critical Damage.
No need to get too technical here, but basically, at level 80 every 35 points of Power should net you roughly 1% extra damage, and every 21 points on Precision should net you an extra 1% chance of a critical strike for 150% damage (or 1% more average damage for every 42 points).
If you’re also stacking Critical Damage then Precision will end up ousting Power in damage per point gained fairly quickly.
Worthy of note though is that world objects, including WvW gates and siege weapons, are immune to critical hits and conditions, making only Power capable of improving how quickly you can break through them.
Also, Precision suffers from “diminishing returns” at higher values, which makes it optimal to transfer some of your potential Precision to Power even with Critical Damage stacked very high.

Condition damage functions fairly independently from the others, and you’ll know easily whether you want it or not and just how badly. Keep in mind that, unless you’re going for heavy defense, you’ll likely be stacking a secondary offensive stat along with it, so your non-condition based attacks will still be effective in a typical Condition-focused build.
Power, under most circumstances, is a universally superior stat to pair with Condition Damage than Precision if choosing between the two.

Critical Damage effectively just improves the value of your Precision stat, and borders on useless without combining it with a focus on Precision. Keep in mind that you should very rarely stack Precision high if you are not also stacking Critical Damage, as Power would provide more damage. The only reason to do so would be to take advantage of an on-critical weapon sigil or trait. In which case, you would typically be sacrificing raw damage for utility, since even a Sigil of Earth in a Condition/Precision build would not provide more raw damage than a Condition/Power build.

Direct and Condition Damage
Comparing the two, Direct deals damage immediately, but is mitigated by armor and deals less overall. It is most effective against light defense builds and for spiking people down rapidly, and counters Vitality stacking better.
Condition deals large amounts of damage spread out, but can be cleansed off prematurely and may be wasted if the enemy dies too quickly for it to run its course. It is most effective against heavier defense builds and for maintaining constant pressure on a target, and counters Toughness stacking better.

Defense
Vitality, Toughness and Healing Power.
Vitality provides the most raw defensive power. Not only will it, per point, cause attacks to take a lower percentage of your health than Toughness, but it also reduces the effectiveness of Condition damage against you, whereas Condition damage ignores Toughness for full damage.
Toughness on the other hand increases the effective value of any self heals you have by reducing damage taken without increasing your health pool, whereas Vitality actually decreases the effective value of self healing by increasing your effective health pool without reducing actual damage received.
With Toughness for example, you might be hit for 200 damage and heal back 100, whereas with Vitality you might take 300 damage and still only heal back 100. And while the Vitality reduces the percentage of health lost due to you simply having more of it, that also reduces the percentage of health healed back.
Every 20 points of Toughness should give a straight-forward 1% reduction in damage taken, and effectively increases the value of self heals by 1%. Vitality though is a lot more complex.
In general, Vitality should provide at least roughly twice the damage reduction per point as Toughness, but reduces the value of self heals by an equal proportion.
The simplest way of explaining the value of Vitality would be to say that, with the Thief’s base 10,805 Health, every ~11 points of Vitality increase the amount of damage you can sustain by 1%.

Healing Power is by far the weakest defensive stat, because it is intended for Support by healing both yourself and allies for more. On you alone it does less than either of the others, but it allows you to keep allies alive more effectively as well.
Unfortunately Thieves have very few means to heal allies. On top of that, even if you stack the hell out of self heals in your build, you would still get more effective value from the heals by stacking Toughness instead of Healing Power.
It does not even allow you to revive allies more quickly.
For this reason, there are no circumstances under which I could recommend taking Healing Power on a Thief.

Between Vitality and Toughness, it mostly becomes a question of how much self healing and condition removal you have in your build. A typical Shadow Arts build, for example, would likely benefit most from stacking Toughness due to the easy access to self heals and condition removal.
All Thieves should benefit a great deal from Vitality though, due to their incredibly low base health.

http://blackwolfbrotherhood.enjin.com/forum/m/9273010/viewthread/4959090-choosing-stats