[Autumn]

Everything here sounds A-Okay, there's only one thing to skirt around carefully and thats:

Dark Imbue:
- Keep the hit how it is.
- Increase the Dark damage on-hit from 2 to '5 per rank'.
- Increase the buff duration from 3 to '2 + (rank)'.

As a just in case measure, I'd make it so the dark damage on hit is split by rounds, you may think why the need to do that but an autopistol mutated into an axe could likely cause issue, not to say that should at all decide whether or not this skill should be buffed.