Your alpha5 build works for me. It still complains about the missing registry keys however I can modify a weapon and load it correctly in the game.

I did notice one problem: I had to change which weapon I wanted to modify for this to work. When I modified a lvl 20 hammer from my inventory, the game would always crash when I tried to load that savegame.

I then modified two different weapons (level 9 one handed sword and a lvl 6 staff) and it loaded just fine.

I went back and tried to modify that same lvl 20 hammer with alpha5 and it still crashed the game. Not sure what the problem is there but wanted to make you aware.