Well as for magic skill lvling it all the way from 25 to 80 will not do so much difference as lvlin any pdmg skill. In short words I wouldn't expect DMG from wind part of the skill to double it would be rather less than that. So DK what was his matt and your mdef, but same hit on pDPS gear would do probably same DMG on physical part

Well the only difference would be that people do not stat mdef like at all, still not worth it, as it would be char statted only for PvP with one melee magic skill..... If you really are so into PvP I would rather recommend to lvl up your mage and switch from Wd/M on M/Wd with magic gear...