I don't think it can interfere with Magic, but then again, I'm not sure about that. Of course, in terms of balancing, it probably should, or Savaniel will be broken as shit, cause he could just mark the weapons and armors of others and then tp it out of their hands, effectively disarming them.
And no, Black Knight can't do shit because he can't fly.
Just saying, but aren't vampires and werewolves, you know....bloodthirsty? Traditionally, when werewolves shift (they can't even control their shifting), they lose all sense of themselves and go on rampages. Vampires are forced to live off human blood AND die in the sunlight for their superhuman strength and possible hypno powers. The aging curse though simply gives him nightmares (which he'll grow accustom to) and makes him age faster (even though his physical strength and such doesn't deteoriate). I'd say...if you really want your super strength and all that...make it something along the lines of...for increasing his strength, he loses more of his life.
Essentially, I was thinking that he ages fast, but retains the physical strength of his mental age. However, he can accelerate his aging temporarily in exchange for increasing all his physical attributes, and he can do this limitlessly, as long as he has 'life' to give in exchange. There needs to be bigass drawbacks to his 'positive' if it's a curse, and it just doesn't feel like aging quickly is good enough.
