These are just some really random ideas that I've thought of while playing the game that I figured might be interesting to see, either because they seem like they'd be really "cool," or because they would introduce a few new play styles. These are generally not particularly serious suggestions, just some semi-random ideas that aren't even necessarily fully thought-out yet.

Guns
+ Laser
> Fires Retrode style lasers for uncharged shot.
> While firing, the player cannot move.
> Pierces enemies, but stops at environmental blocks (will still destroy breakable objects, though; just doesn't pierce them).
> Only one shot can be fired at a time.
> Useful for attacking tightly packed crowds of enemies.

+ Spreadgun (Puppygun)
> Fires a spread of shots (3* fires 1 shot, 4* fires 3 shots, 5* fires 5 shots)
> While firing, the player can move only slowly.
> Two shots in a clip.
> Visually could appear to be a miniature gunpuppy.
> Useful for attacking large crowds of enemies at once.

Shields
+ Note that these shields replace the normal shield functions with alternate uses. This is primarily to make it possible to perform offensive actions with just shields.

+ The Heavy Pusher
> Shield-bumping strength to the player's front is dramatically increased.
> When shield-bumping enemies in front of the player, those enemies take an amount of damage between that of gun and sword averages.
> Can only protect against attacks from the front (like Trojan shields).

+ The Plasma Pusher
> A variant of the above shield, except that, instead of dealing damage upon bumping, this shield can fire off a beam after the player defends with it for a short time (to charge it, really).
> Similarly defends from the front only.

+ The Charger
> Yet another variant on the "protects from front only" shield. This shield allows the player to perform a running charge attack, similar to the charge attack by trojans or in TF2 with a Chargin' Targe. Hitting an enemy with the charge will cause some AoE damage and knockback to the other enemies nearby, while the one hit will sustain massive damage and knockback.
> Not sure how to limit the time between charges (thought of a charge meter, much like in TF2, but that seemed like it wouldn't fit with the rest of this game).

+ The Picker-Upper
> Player loses shielding functionality except for shield-bumping.
> If the player comes up to a stunned, shocked, or sleeping enemy, he can use his shield to pick it up, after which, he can then throw the enemy like he would a pot. Thrown enemies will take large amounts of damage (about upper sword-average), while enemies that are hit by the thrown ones take gun-average damage.
> Enemies that have been picked up play flailing animations, but otherwise don't do anything. Perhaps, to add some tension to using the shield, the player might drop the enemy when it is no longer stunned, shocked, or sleeping.

Helms
+ Some sort of companion helm for Radiant Silvermail (as in, combined piercing and shadow defense).

Armor

Costumes / Accessories
+ Top-hat
> A Costume helm-slot item.
> It's just a top-hat attached to a generally non-descript helmet, like the Chapeaus.
> Really, it's included alongside the Mini Top-hat just so you can wear a top-hat on top of another top-hat (though I'm not sure if having a head-top slot would really be possible with this item).

+ Valk Wings
> Head-side slot.
> Essentially, the wings from the Valkyrie Helm line taken off and made into accessories.

+ Face Guard
> Head-front slot.
> What would be considered a mouth guard, if Knights have mouths.

+ Miniature Top-hat
> Head-top slot.
> A small top-hat.

Just as an extra note, in case people didn't notice it at the beginning of the post, most of these suggestions aren't particularly serious and are just small things that I think would be interesting to see.