Eh, seems the word "damage" was forgotten there (-5% damage)...
And for what the intention was... well, I wouldn't mind knowing that from Larian too. Early in Beta they gave increasements to the various classes (man-at-arms, spelltypes), but of course that's problematic with the x spells per level and people permanently loosing spells if their traits changed. So they gave them new bonusses, and several of them are really dubious/useless.
