I think it is based on the dmg of the Java for one reason:

With my old Javazon, I traded a shit load for gloves that added +2 to Java Skills, an upgrade from nothing to thse skills and it only added like 50 dmg or something very very miniscule. It surprised me and pissed me off too!

Let's just make a JAvazon and check out both options, and see first hand! I still think a Cruel Java would be better, since you can get much higher dmg (If you don't have Eth Titan's), but with the lack of all those great skills.

I'm probably wrong, but I'd like to know for sure!