I am a PvE Player myself. I like fighting Vanaduke alone and playing Roarmulus without people because that is freaking annoying with people.
I just had the idea of the PvP 'shields' being in PvE. I dunno how you would get them, but I want them lol

Striker Shield (Thruster)
Basically the same thing. There isn't really any problem with this, but the recharge time should be shorter in PvE and the ASI and Damage should be lowered to low
I think a shield bash would be cool, so for a shield bash - it would take out half of the shield and then give you a small attack bonus for a couple of seconds.

Guardian Shield
No HP bonus, No HP regen. The HP regen would be changed to a defense bonus to all who is in the circle, including you, which will help you reduce damage when the shield breaks. It would last about 3 seconds long when getting into the little "aura" space. The penalty of the gun speed I think should go away, but who knows - I usually gun with Swiftstrike :P This shield should also not regenerate like the other shields, but slower. Way slower. The defense should be all normal.
The shield bash should just be larger like the Torto shields and does more damage and still stuns.

Recon Shield
I think time should be reduced for PvE because monsters are stupid and can't track where you're walking when invisible. Reduced by a lot too. Maybe by half? The death mark should last a little longer and the defense break is pretty useful once you think about it in PvE. ASI in guns and CTR in bombs should be lowered down to low
The shield bash should take half the recon shield out and then all enemies in a small space get a random status ailment.

So yeah, I don't know if this seems overpowered, but I am getting tired of the regular Swiftstrike Buckler being the meta. We need variety!