*Bump* for a 4* star version. Currently there is 4*/5* shields with sword damage but none for gunners.
The shield: http://wiki.spiralknights.com/Swiftstrike_Buckler
while only sword users got something to carry on to tier3 dungeons: http://wiki.spiralknights.com/Shield
Swordsman are the only ones that would really need to take advantage of a shield. Bombers can't use them much in a fight, and Gunners fight at a distance.