I dont know if "reduction" is the correct term,as I dont remember.
Im talking about how daggers are 5, staves are 10, axes 15, etc. So when I saw this attribute appear on some boots after I did "enchant weapon" with a charm, I wondered if it meant anything?

From what I can tell "Speed" is the attribute weapons get to indicate how much faster than normal they are. A Dagger, reduction 5, speed 2, would attack every (5 - 2) = 3 time units.

I still dont understand why a ring or boots would have this. A bug maybe...