I have no gripes over the three classes there are now: Gunner, Bomber, Swordy.
But I love player-created/custom classes. For example, I'm a Gunner/Medic. I wear a Sunset Stetson, Vitasuit Deluxe and a Heavy Plateshield. I gun and stay out of harms way to preserve my large amounts of health, then give it to players in the melee who have better armour than I but have happened to fall in combat. Heavy Plateshield is great for tanking in and saving such people. I love shields, and I've gone for the biggest shield around, merely because I just like the look. Also I love how much damage it can soak up in the last wave of the last round of an arena that fills with gremlin bombers. I can just tank through the bombs and my shield hardly takes a scratch.

However, I think that if a select few custom advanced shields took up a weapon slot like a sword/gun/bomb and could be used to more than just defend, that would be pretty trippy. Not to mention it would encourage said shield wielders to use their shield more. I can't decide wether the shield would over-ride your normal shield key, (X by default) or if you would switch to it in order to use it. I'm thinking the former is probably the most practical option. Some shields I came up with for example:

GUARDIAN SHIELD:
When the shield is raised, it provides nearby teammates with a minor defense (or damage) boost. (and would be no-where near as large as the guardian in LD's shield, thinking more the size of a 2* Vaporiser.
This would promote teamplay and sticking together (although that does make the team vunerable to area attacks, so the shieldbearer would have to think when would be an appropriate time to use it, because a damage/defense buff just BEGS to be standed in especially to sword freaks wielding DAs :P)

SPIKED SHIELD
A proportion of the damage this shield takes is reflected upon the attacker.
This would promote more shield usage in a duel with a monster, rather than just slamming the crap out of the monster without consideration to ones own safety like many new players toting swords do.

SHADOW SHIELD
Raising this shield allows the player to move through enemies (or maybe obstacles like spikes and destructable blocks?) Shield slowly degenerates when raised, instead of regenerating.

STRENGTH SHIELD
Shieldbumping enemies deals damage to them.
This would be handy for someone who likes to "juggle" enemies by bumping them away from team-members.

POWER SHIELD
Raising the shield charges the currently selected weapon, lowering the shield fires the weapon. Charging a weapon in this manner causes the player to still move at shield speed, rather than whatever speed the player would usually move at if they were charging said weapon. This means weapons like the Magnus and the Graviton Bomb can gain manoverability with the shield charge.

CHARGE SHIELD
Shielding causes the shield to charge, upon releasing the shield the shield delivers some form of attack, be that a 360 strike, a knockback stab in the direction the shield is facing, or a stun/fire/other status dealt to all enemies touching the shield before it was dropped.

Sometimes the best defense is an offense, right?

These ideas are starting to remind me of Beat the Vandel Buster.

Ideas, Gripes, Niggles, Suggestions, Likes, anyone?
But if someone suggests a heal shield I'm going to punch them in the visor.