Lack of the utility of the Assault stance;
Poor skill set of this path.
Explain why it is an issue
Whole gameplay of the Assault stance consists of spamming Grim Slash, Brutal Assault and reapplying dots. Clearly there is a lack of possible rotations. Also the stance itself limits the variety of skills.
Only Grim Slash with the Wrist Slash tactic provides an interesting debuff but it is not enough for the overall utility.
Propose a viable solution to the problem
Counterstrike


I can bet that there are SWs who have never known that such skill even exists. This ability has a long cooldown (20 sec) and nowhere close to be spammable, also it has the lowest damage comparing to other skills and only one extra use - interruption.
The game has a lot of skills which can interrupt casts but all of them are better (some of them are aoe and can't be parried/blocked, some give a damage boost or debuff a target and etc).
Solution:
Give this skill an extra effect:
A quick strike which deals X damage to your target and interrupts any ability that they were building up. Also you will drain 50 of their Action Points into yourself.
Considering that this skill has a quite long cooldown (maybe should lower it in addition?), it would still have a place in any rotation since it will become more flexible to use, not just only for interrupting. Also it would help with an enormous AP starvation of the Assault stance gameplay.