Shield Question

If you put a plus on a shield, does that have any effect on the blocking rate, etc. of the shield, or does is just raise the defense on the shield?
This leads to the next question, is an overenchanged shield a good investment, or is it better to keep the pluses on the armor only?

atm, + on a shield puts up defense only. defense rate is unaffected. dont buy + shields unless you are a paladin, DA, TK or SK.