http://forums.ddo.com/showthread.php?t=318820
Short version:
Switching handwraps screws up the to hit and damage bonuses of handwraps. You can see these values in the bottom of your inventory screen and can test it for yourself.
Here is an annoying but working fix:
To fix your To-Hit:
1: switch to your desired handwraps
2: drink a guild heroism pot (will not work if greater heroism has been cast on you), or
3: switch to the goggles of insight from korthos, then switch to your normal goggles, or
4: get a bard to play a song on you, or
5: get a ship buff that gives you a bonus to your to hit (training dummy, 3 dragons), or
6: cast greater heroism, or
To fix your damage bonus:
1: switch to desired handwraps
2: ship buff dhakaani vigor, or
3: bard song, or
4: switch to/from bold trinket?? (not tested but should work IF you do NOT have the dhakaani vigor ship buff as they do not stack)
Note: switching to and from the sora katra set from lordsmarch will fix both to hit and damage bonus
Explanation of fix:
To fix your bonuses, you need a buff or a set bonus that increases either or both of your to hit and damage bonuses.
Devs know about it and are working on a fix...