At 1st level it appears a little powerful, I'll grant you, but this system has to scale all the way up to 10, 15, 20, and deal with what are basically epic level effects. And right now the scale starts a little high at the beginning. Fairly certain at the top end it could deal with being stronger, though.
I'd have to create and hand out a lot more runes to avoid stacking, which is one of my current arguments against it. Right now, you couldn't have a second carved rune at 1st level without changing the base class progression.
I'll see what I can come up with for feats.