I recently purchased a set of +6/+8 gear and I've noticed that my attack when I use the gear decreases every time I repair my items. When I started out using the items I can hit 20k+ on the swordmaster. Now I can only hit 8-9k.
One striking example is that today at 5:34 game time I was killing the swordmaster. I went outside to repair my items halfway. At that time I was hitting around 13k. After I repaired my items and went back I was only hitting 8-9k. I did not change anything in between; not chi, stig, potions, dragonsouls or anything.
I'm not sure if my defense has gone down as well.