I played through with a DK warrior (with a 2 handed sword) and did not invest in Armour Usage or Evading; they probably could have helped a bit, but I didn't need them, and was saving skill points for a possible change of build. I'm not sure which would be better, or if splitting points between them would be better than maxing one. Actually, I don't recall that being debated around when BD was released, either (weapon expertise skills were; in that case I invested a couple points into damage and accuracy, for bow/crossbow maxed Reload Time, and ignored the rest).
Playing again, I would have the DK be a bow archer, so I could invest more in agility (since he wouldn't need strength for equipment requirements).