[Autumn]

I believe I know this bug, due to a recent screenshot that turned up, it changes your normal basic attack into a different weapon almost completely, it displays as your regular weapon but in actuality it could be something completely different, I've been able to use Ashe's Nobunaga for this very reason. (Which is a very cool weapon btw.)

It'll happen randomly on the reboot still, BUT this is definitely the source of the bug, basic attacks being magic damage likely mean your weapon turned into a tome per-say, and basic attacks just straight up not working at all probably meant it turned into an incompatible weapon and just fizzled out completely.