I think as a cool feature, shields should add a "blue" health bar over your current one to make you feel more at ease if you are shielded.
Example:
http://i.imgur.com/QifUBMd.png
Perhaps different kinds of shields using slightly different colors.
Also, for TP/MP restoration it should look like this. That way you know you are getting those buffs as well.
http://i.imgur.com/onHPozK.png