It doesnt boost your weapons damage by 10% when you have a stolen skill, it boosts the damage of the stolen skill. The wording is probably left over from early beta when stolen skills replaced your weapon skill bar and were an actual carried item. The only skill i could see really getting a benefit from this is whirlwind axe from warriors, since it does good damage. The other half of the trait relys on rng, and is on a 45 second cooldown untraited (not 30s as previously mentioned) Nobody likes rng.
The second part of sword #2 is identical to the second part of Shadowstep utillity. It is intended to have at least a 1200 range on return, though often one can exceed this range, other times it will 'return' you as far as it can backwards, but not to your original location. In addition the skill has seem to have slightly different behaviors through various patches since beta.
.Those are all utility infusions. rings and back come in either offensive or defensive. only amulet has offense/defense/utility variety
so they probably do stack, except only amulets can use the infusion and can only wear one amulet.
The interrupt on headshot is a great harassment ability. We can spam it as long as we have initiative. As mentioned above, it isn't there to offer significant control. It's there to let you interrupt the enemy actions.
Black powder is a great tanking utility because blindness is a completely "miss". It's full mitigation for a hit, and it's AoE. This means you could effectively "dodge" the first attack of a group of enemies in proximity. It also blocks projectiles, so it's a great shield to make an enemy close range with you- just drop a smoke cloud and stand inside. Similarly, you can drop a cloud on an ally to protect them from projectiles (or drop it on their attacker to blind him/her).
Another big benefit of black powder is the smoke combo field. You can set up the smoke field which offers you a stealth opportunity with heartseeker (a leap combo). You can also drop the field so that friendly projectile combos will pass through it: this creates blinds on hit. Lastly, whirl combos inside a smoke cloud will creating blinding bolts. These combos really add a lot of value to black powder in both solo and group settings. It's also a great way just to practice using fields both in setting it up fo rothers or taking advantage of it yourself.
Just to correct, black powder does NOT block projectiles, smoke screen does that.
black powder- smoke field, pulsing blind (no projectile block)
smoke screen- smoke field, blocks projectiles (not a pulsing blind)