Might as well sneak in unique disabling mechanics, like precision strikes that disable all special abilities (including CC, defensive cooldowns and mobility) for X seconds.
I've tried to stick with functionality that already exists in some form or another or is an extension of existing abilities. Disabling specific class functionality doesn't really exist in the game at the moment and wouldn't be useful in PvE (since said "special abilities" are intrinsic mechanics that can't be ignored) while being specifically disadvantageous to some classes more than others in PvP (imagine disabling survivability CDs, which would have negligible effect upon Sages since they have none, possibly excepting the new Force Barrier, while it would have a major effect upon Shadows, Guardians, and Sentinels), not to mention it's hard to define "special abilities" since it's not an explicit category of abilities (ex: is Defense Screen for Scoundrels in the same category of abilities as Saber Ward for Guardians?). As far as the game is, mechanically, concerned, there are only attacks (CCs are actually attacks that deal no damage), heals, and self buffs so, in order to do anything like you're suggesting, you'd have to either create an arbitrary list of abilities that would need to be kept absolutely up to date or go through the game and create separate categories of self buffs and attacks exclusively for that mechanic to be implemented. Either way, it's more work than it would honestly be worth since it would, functionally, be only useful for PvP against specific targets.
The "new" mechanics I've added are simply new for players: a disengage used by one of the ACs (yes, it's for a melee AC, but it's additional mobility coupled with a survivability buff and it's actually an integral part of one of the specs and makes for a really interesting playstyle with it; as far as the game is concerned, it's a knockback on yourself from your target), a teleport/nuke ability (a targeted AoE that teleports or leaps you to the locus of the attack; limited to a 10-15m range to prevent it from being abused in PvP; this is pretty much what Toth and both Kephesses do with their leap/nukes), and one spec gets an PbAoE pull (10m range that sucks every enemy in, just like a range shrunk version of the AoE pull that the miniboss droid of MP does).
The primary differentiation I've done is in creating largely unused priority/rotation schemas and the interaction of two discrete resources (the ACs both have a set up that uses one resource largely identical to a Shadow's Force resource and a second largely identical to a Sentinel's Focus) as a method of utilizing those 2 resources. It's not really necessary to reinvent the wheel when designing a new class, especially since, honestly, there's still plenty more that can be done with the existing toolbox: the existing mechanics in the game actually allow for the creation of pet classes that don't require any tweaking to the existing systems as long as you know which abilities specifically to mention using and how to manipulate them with other existing systems (for example, a pet could be summoned through the use of an unlimited duration self buff cloned version of the Athiss bioanalysis crew skill benefit which places a buff on you that summons an akk dog to fight for you; manipulation of its AI to control who it attacks would be accomplished through cloned versions of the "passive" and "attack" companion abilities which either zero out all threat or maximize the existing threat for the current target; my next project of interest when I finish this is to flesh out *that* class idea).