Here are some simple ideas that I would really love to see happen to subtlety, which shouldn't cause any imbalance issues, and should add to the uniqueness of the spec.
A) Take gouge off of the DR with sheep and more importantly, sap. Sap can stay on DR with sheep. Just take gouge off dr with sheep/sap.
Why? Because using gouge in arena is very skill demanding (you aren't going to be using it on the target you're dpsing 95% of the time, and it's a melee ability, so it means you have to maintain a close range to who ever you want to use it on and do quick target swaps). It's very clutch when used correctly, but when paired with a mage, it often screws you over by putting a DR on sheep. Gouge doesn't really need to be on sap DR, an Imp gouge is about the duration of DR'd sap anyway, and costs 5 seconds of energy.
Not to mention, and Akrios brought this one up, to use gouge, you lose probably 5k+ damage through white damage, the energy cost, and the global, not to mention the varied travel time which could lose you more.
B) Replace filthy tricks, or waylay, with this: Reduces the cooldown of gouge by 2.5/5 seconds OR
Increases the duration of gouge by 2/4 seconds.
Why? Because, especially if gouge no longer shares DR with sheep, it could turn a subtlety rogue into a very powerful utility, which I honestly believe is the vision of the spec. Using gouge effectively in arena is very skill demanding, and increasing its effectiveness would give a skilled subtlety rogue a unique potency. Reducing the CD is the weaker of the two, especially in 2v2, because the DR will stack quickly, especially if gouge stays on DR with sap. Increasing the duration would be a pretty good change. It would be like sheep, except it's melee (huge requirement), lasts 9 seconds, and has a 10 second cooldown (can't just spam it if they trinket). Not very OP.
Why waylay or filthy tricks? IMO, waylay is pointless. It pretty much does what crippling does, and with the poison buffs, I have no trouble keeping crippling on my target. Filthy tricks just has no real use in arena, because you most likely aren't going to be in a match long enough for the 5 minute preparation cooldown. It obviously has no use in PvE.
This last suggestion is a lot more controversial than the first two, but it's pretty important.
C) Shadow Step now useable while rooted (ie. frost nova etc). Also removes all snares. Perhaps also makes the Rogue immune to snares during the 3 second speed buff.
Why? Shadow Step used to be useable while rooted, but that was removed with WOTLK. It was essentially removed because ShS rogues were OP in s3 and s4, but the change came far too late to make any sense. Removing snares honestly should have gone on ShS from the beginning, because -- and many top rogues will back me up on this -- you'll often Shadow step too far behind the target to hit them before they get out of range, due to a snare on you. It makes the ability near worthless a good portion of the time.
You know, reading my own gouge suggestions, I try to really work them out in such a way that they won't be too powerful, but most people must be going, "what? gouge? what's even the point?", because really, very few rogues even use gouge in arena. It really is difficult to use it effectively, and i like it that way. It's skill demanding, like kicking a pally's heal, while you're dpsing his DK. You have to stay close to him to do it, and you have to have very quick reactions to pull it off.
I think changes A and B would certainly be fair, and very fun. I think C would give subtlety the mobility it needs to be an effective utility spec. Notice none of the changes involved an increase in sub damage dealt, and it's because I think sub can be viable by simply giving it enough utility, and not just more cookiecutter burst.
btw howd darkfall go?
Good read