Yep and yet he can't defeat his father

so the sword is like a butterknife if the opponent doesnt have any powers?

No, the opponent is the butter, and the sword is the knife

5000/10000 means he can deal from 5000 to 10000, by absorbing magic i mean

It'd be cool if the sword could then use the magic it absorbed, sorta like the Sword of Gryffindor

It can.

I mean it becomes more powerful more magic it absorbs, if it were to absorb a very very very powerful magic, then the next hit would be able to oneshot anyone, just that it would destroy the sword in the process