Major characters with power-controlling powers

[BWTraveller]

I was wondering if there were any real good anime, manga or light novels with major characters who possessed powers, but not personal powers but rather an ability to impact the powers of those around him/her, or to use others' powers. And not power-nullification, that's been done quite a bit and while it's great I'm not really looking for that. A great example is in the old anime and card game Aquarian Age. It sets up a world where five factions consisting of individuals with various mystical powers are constantly fighting for supremacy, but recently a new group called "Mind-breakers" arose who don't have personal powers but can awaken others' powers, or strengthen or weaken them, or even perhaps force their activation. The game places the players as such "mind-breakers" with collections of allies that are deployed in combat, while the anime sets up a young man who doesn't know he's awakened to mind-breaking powers.

There's also Telepathy Girl Ran, an old series in which the heroine's boyfriend rarely shows much power of his own, but he's repeatedly demonstrated an ability to enhance or suppress others' powers.

Oh, and Magika: Swordsman and Summoner. This one's a little odd. Magic returns to the world, and a school develops to train magic swordsmen and the girls marked to become summoners and contract with the 72 pillars of Solomon. One guy is marked and when he tries to forge a contract an unknown being emerges that reveals to him that she's the "Lesser Key" that allowed Solomon to control the 72, so he has no power of his own, but if he can get contracted girls to give him their full trust and loyalty then he can use their magic as his own. The Key wants him to make them all into lovers, he wants to take the hard route of making them incredibly close friends, at least until things get dire enough that he decides they don't have time for the hard route.