Quirk Limitation

Akira's quirk has certain limitations, like;

-He can't affect/dabble on the Concept Of Death.

So essentially, he can't just walk up to a dead person and say, "Revive", or say to a living person, "Die".

-He can't steal/evolve quirks.

Even if he can steal quirks, he wouldn't do that, as he thinks it would lessen his lifespan.

As told by the Fourth User of OFA, his life force was depleted, his body crumbled, and he didn't live past the age of 40.

He can't evolve quirks. I don't really have a "logical" reason. It's just that it would make him insanely overpowered, more than he already is.