Some funny shield ideas:

The Graviton Shield would suck enemies towards you, instead of bumping them away. Super dangerous, but super useful, too.

The Phazewarp Shield does not really absorb damage, but makes you untouchable for a very short moment. Everything passes through you and you can walk through enemies and over spikes, traps and through brambles and so on. While it is active you can't hurt enemies, of course. When it wears off, it can't be used for short, because we don't want people to run around all day, tapping the shield key and being invincible.

The Battering Shield makes you leap a long way forward and push enemies out of your way, like the Charge of the Trojan does. Afterwards it needs a short pause before it will work again. During the rush forward, you can't be damaged or you can just be damaged from behind, dunno.

Force Field shield, that does not bump enemies away, but hurts them instead. Different types could be made, for different damage types or inflicting status.

A Deflector Shield could be a more dangerous one and could bump enemies away and hurt them, while it wouldn't absorb any damage at all. Obviously only for pros.

The Energy Converter could transform the force of attacks into health, but it will work only for short and has a pause. So while it's activated a monster that hits you actually heals you.

Btw, the Health Generator can restore a coupla health bars, but can't prevent any damage. Again, it's one of those who need to pause for a while.

The Super Charger has bad stats (i.e. it's only 3 star or so), but while you shield it also charges your weapon. When you stop shielding, it automatically triggers the charge attack, if the weapon has been charged up completely. Another flaw is, you can't switch weapons while shielding with this thing.

The Honey Pot is super shiny and powerful and has lots of resists, but whenever you activate it all monsters in a wide area wake up and want to attack you. It's like when you get a nosebleed while swimming with sharks.

The Shield Of The Fallen is extremely powerful, but has a chance to inflict Curse on you, whenever you activate it.