I always liked "mark a section of the map for artillery strike" mechanics even if they're sort of passe now. In RO2 I think you got some sort of warning, so it worked mostly like temporary area denial.
I'm a big fan of Mario Kart 64's bananas I can't decide if they'd be awesome or horrible in AoT, though.
JC2's hookshot is pretty great- it deals a decent amount of damage and grapples the enemy to you like Scorpion's "GET OVER HEEERE" harpoon. Might be hard to balance for Telos, though, it would be pretty annoying to get pulled every-which-way by 5 enemies all game.
In the same vein is HL2's gravity gun. I don't know quite how it could work here, but damn if it's not fun.
The AWP from CS is nice too, I think. Super powerful, super satisfying to shoot, but it has a cooldown that leaves you vulnerable, and you can only shoot with any accuracy while scoped in and holding still (though you can be moving through space, just not by using movement keys.)
I'm also a big fan of huge fuckoff hammers that take a while to wind up but do huge crushing melee damage. Maybe something like this in AoT could lend momentum to the target?