When you install Psi from the curse launcher it turns the player's visible arm transparent in first person mode. I have tested this both with other mods as well as with only Forge and Psi installed.
fml-client-latest.zip

Thaaaat's a forge bug.

^ source? 0.o

report to the forge repo them with screenshots

I've reproduced it with only forge in a dev env.

wasn't this already reported by V? She said something about that...

issue i was thinking of: #147