After deleting the skills, maybe the muscle memories are still there and the MC can still perform them to a certain extent. If MC still use and practice it frequently, maybe MC won't forget them permanently or master them organically. This could prevent over reliance on the system.
What classifies as weapon? What makes weapon, weapon? If he can use anything as weapon then maybe he can get special effects from random objects too. People use car as weapon. Can he touch a car and gain fast travel? Lol
I found a fake author like that recently. This guy translated Chinese, Japanese or Korean novels using chatgpt and acted like he wrote them. So shameless.
He would post some chapters for a novel and after a while, if it didn't gain traction he'd delete them and steal another novel to...