Thats the problem with crafting. It causes the end item to be way higher minimum level than regular generated loot.
I'd suggest making each increase only +1 instead of +2. Or making the + 1/2/3/4/5 Enhancement only increase by it's amount.
For INstance: I created a +3 Holy Heavy Repeating Xbow of Pure Good and cannot use it until level 13. When it should really be min lvl 10.
I know about the Master Craftiing item. More grind (IMO).