is this just a thing with O'saa? I tried starting with Red Virtue, and like I can use it in one fight before it disappears.
tho I just realised I had all contestants moonscorched/dead option on so maybe that's bugging the weapon out?
follow up: can confirm the moonscorched/dead contestants option does remove your chosen starting weapon, I get there is a disclaimer about it being experimental, just wanted to see if this was at all possible