thx for the hint ! =)
i tested it again in duels/caergate. with ME, DE, SW and WH
summary: with 0 resistance and 0 pvp-def/-void, chakra-atk against me (and others) is reduced, too. the dmg-gap is around 1/4 of the one it should be =/
it was told to me, void also reduces chakra dmg, but that dont makes sense to me. resistances would be useless thereby. "normal" def and void is for physical dmg part, if i dont have a error in reasoning.