Well...if expand a shield's shape is very difficult and sure...it may cause some new problems.
Then how about just keep the shield's shape but only bright a small area where it being hit?

As I said in your other thread:
I think for now the shields are fine, they're not shabby, and they're not state-of-the-art, but I think other graphical aspects need more attention than this one.

advise: verb. The act of giving advice.