Sadly, I have only one shield to contribute, but saying that,I know it is a rather efficient shield.
-TDR-550XC Impenetrable Panacea Shield
--Level 48 Variant
--Recharge Time: 181
--Other abilities: Quick Health Regeneration!
--Personal Notes: Yet another rare find in Borderlands that the game spawned. In this case, it was a level 2 variant. All I did was modify the level variant to 48, and this was the result. Huge shield with a decent recharge rate with quick health regeneration . They only way you are dying quickly is if you're playing the General Knoxx DLC, you run over multiple corrosive barrels with your vehicle, if you're hit by a vehicle, or fall off a cliff. So it is very rare, but the game can spawn this shield.