/pet focus and /pet no cast atm do not work at all. I have the AA maxed and have for the longest time but the command doesn't do anything. /pet no cast wouldn't get too much use but /pet focus is a major help especially while soloing though it can see raid use as well so i would love to see them fixed =D
/pet hold btw works perfectly fine, probably because it's on a separate AA (/pet hold is "Pet Discipline" with only 1 rank, /pet focus and /pet no cast is "Advanced Pet Discipline" with 2 ranks, 1 per command.)
Basically /pet focus acts exactly like a /pet attack except it stays on the target until either the target dies or the pet is pulled off with back off or /pet hold. This way the pet doesn't jump between 10 different mobs instead it burns a single target down. You can either use the command mid combat on a target or use it to replace /pet attack altogether. /pet no cast does exactly what it sounds like lol, makes your pet not cast spells, it will still proc however.
Thanks for your time =D
-Milein