I had an idea with refining and slotting but the first question i must ask is..
1. Can i make an item with more than 4 slots? If so..
2. What's the max value? If yes, then the idea is..
When refining to certain value, the item will gain a slot. So for example..
+1 Knife to +2 = +2 Knife [1]
+2 Knife [1] to +3 = +3 Knife [1]
+3 Knife [1] to +4 = +4 Knife [2]
and so on..
The 'add slot' on z,x,c,v,b,... value would be customizable of course.
My personal preference would be, even number refine starting from +6 = 1 slot
+6 [1]
+7 [1]
+8 [2]
+9 [2]
+10 [3]
These extra slot would be on top of the existing slot on the base weapon. If you start with +5 Knife [1] then on +6 you'll get +6 Knife [2]..+8 Knife [3]..+10 Knife [4]
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Cons:
- Existing card in weapon will be gone..unless the script is so great you can keep it.
Pros:
- Yay 'smiths