Hello Dan! I hope you will check back here.
I got this latest Attrition version since I wanted to play again fully.
The weapon and player level XP bug happened to me as well even with your hotfix ( I got it and restarted).
In the original campaign I got to Warp Factor and right at start in the small room flanked by the two elevators after the battle with the small army of Sentry Drones a Super Trooper spawned.
This guy yielded like 4k XP and the weapon that I was holding at that moment quickly gained a new level.
Worse is that it got "tainted" and now whenever I fire at an enemy with that specific weapon that I held when I killed the Trooper it always gains a level instantly and my player level also grows very fast along with it...
The other weapons that I didn't use on the Super Trooper are fine. I loaded and re-tested with a lot of them even the foot and the same thing happens...Trooper dies yields a lot of XP and the killer weapon gets stuck on leveling up fast. Leveled the Shotgun to 13 in a few shots and then it stopped...or so it seemed.
Obviously I killed more of these new Super Troopers (which are awesome btw) up until this point but it happened now in that specific spot. Maybe the spot is irrelevant since monsters are generated randomly but I provided every info I could. Maybe the monster is irrelevant as well and this could happen with any foe.
Could you please take a further look into this? I really want to play through your Mod again with this new version.
Cheers!