I like it! "Metal man" is weird but cool, and it's fun to think about why/how my character would have this power. I do however miss the ability to change weapon materials a bit; it seems like he should in some way interact with silver/cold iron/adamantine, because that's where the idea of "metal" is most relevant to most adventurers (aside for their theme song, I mean). I love Lead Screen.
What if 'metal man' let you turn yourself into different metals, instead of (or along with) boosting different ability cores? I suppose that could get complicated fast, though.
Yeah and eat up words.
The Metallurgic shift went away because I changed what I was switching out for Metallurgy. I no longer felt it necessary to use it as a balance to the heavier loss of Mutagen.
Also I figured I just turn it into a discovery instead. Also along with some ideas that would make more discoveries that flavourfully suitable to the archetype.