Spiral Knights does a pretty good job of including a variety of weapons with different styles and advantages, but I'm pretty underwhelmed by the armor and shields. A defense boost against a different damage type or status effect is just not terribly exciting, and most of the special abilities on armor and shields are actually enhancements to your weapons, which are all very similar, don't really make sense, and have a number of gameplay problems (locks people in to a single weapon type, very hard to balance without making them either mandatory or trap options, just look at how disproportionately popular the wolver line is, etc.)

It's probably not realistic to expect a major overhaul of armor and shields at this point (especially one that takes abilities OUT), but I like imagining interesting abilities, so I decided to waste some time brainstorming ideas for shields and armor with distinctive special abilities (that are actually related to their function). All numbers are ballpark examples and would probably need tweaking to balance (I'm also assuming some items would have lower base stats to compensate for stronger abilities).

Peruse at your leisure.

SHIELDS

Force Wall: This heavy shield is amazingly tough, but it loses health constantly as long as it is raised. Compared to other shields, this can block far more attacks before breaking, but only as long as you put it away when you don't need it.

Second Wind: This shield regenerates health especially quickly, and it won't stay broken for as long as other shields. When you can't find a safe spot to rest for even a few seconds, the Second Wind is your friend.

Tenacious Targe: This little shield just never gives up. If your shield is broken, you never take damage from the attack that broke it. Even after the Tenacious Targe is broken, raising it will still reduce the damage you receive, though it will no longer protect you entirely.

Chronobuster: Raising this shield sends ripple effects backwards through time, instantly healing damage you received in the moments just before you raised it (even damage that should have killed you). Effectively, the Chronobuster will still protect you from attacks if you're a tad late in raising it.

Shadow Shield: The Shadow Shield builds up a lingering charge while raised that will continue to protect you for a short time after you lower it, giving you protection at the beginning of the following combo or sprint. This lingering protection lasts longer the longer the shield was raised, but hits against it still reduce your shield's health as normal.

Tortoise Shell: This versatile shield can be used even while you are attacking (or charging an attack), letting you fend off unexpected attacks or make daring offensives into enemy hordes. However, it reduces your attack/charge speed while raised, and the shield takes double damage from each attack it blocks while you are attacking or charging.

Eagle's Emblem: This striking shield allows you to move nearly as fast while it is raised as you can normally, so you can still run away or dodge attacks while using the shield as a backup in case you misstep.

Serpent's Ward: The Serpent's Ward elminates recoil from blocking attacks, so that you won't be knocked back or stalled when hit. This allows you to counter-attack more quickly, and also to move much faster through spikes or other hazards while blocking.

Bull's Bulwark: This hefty shield is more effective at knocking enemies away when you first raise it, and establishes a light repulsion field as long as you continue blocking, pushing nearby enemies away from you. This helps to escape from mobs, and lets you more easily corral enemies for crowd control.

Spider's Lure: This subtle shield has reduced knockback and pulls nearby enemies closer to you while it is raised, generally leaving enemies in the perfect position for counter-attack after you block them.

Beacon's Bubble: This powerful shield not only protects you, but also creates smaller protective bubbles around nearby allies, allowing you to protect other knights who are not ready to shield. With the Beacon's Bubble, you can rescue allies that have over-extended or whose shields are broken.

Emberburst Shield: This superheated shield has a chance to set enemies on fire whenever they contact it, either by bumping against it or striking it with a melee attack. Alternate versions inflict other status effects.

ARMOR SETS

Titan's Togs: You can stand tall in these giant's clothes; each piece of the set provides +1 max health per tier more than other armors, and also increases the health bonus received from vitapods by 50% (wearing both pieces doubles the effect of vitapods). Knights typically heal several times their max health during a clockwork run, and vitapods don't increase your current health when picked up, so this doesn't actually help that much over the long haul; however, it greatly increases the damage you can survive in a single battle, protecting you from the occasional blunder or lag spike. They're also great for boss fights.

Armor of Regrowth: Each piece of this symbiotic armor amplifies all healing your receive by 25% (stacks to 50%), whether from hearts or health capsules. The complement to the Titan's Togs, this armor helps you survive the long-term war of attrition, but leaves you more vulnerable to a sudden spike in damage.

Guardian Plate: The helmet of this set ensures you take only half a bar of damage from any attack while you are at full health, making it easier to heal if you spend most of your time near full health. The armor negates fatal damage and leaves you with half a bar remaining if you had at least one full bar before being hit, giving you a second chance to escape or heal when a knight wearing different armor would already be dead.

Wishing Mail: The helmet of this set projects a powerful force field that completely negates a single hit, but takes a long time to recharge (perhaps 1 minute; recharges instantly on party button or elevator). The armor allows you to slowly regenerate health - but only up to the amount you had just before the last time you took damage (for example, if you have 10 life and get hurt, you can regenerate to 10; if you're hit again when you've only gotten up to 8, you continue regenerating, but now only up to 8). You are instantly healed up to the current regeneration cap when you press a party button or ride an elevator. Thus, the helmet counteracts the first hit you take, and the armor counteracts the last hit you take. Good if you're only hit occasionally, bad if you get hit many times rapidly.

Giant Slayer Armor: This armor set protects you against powerful blows, with a defense that scales to the amount of damage you take from a single hit. Great if you hate lumbers and trojans.

Horde Breaker Armor: The helmet of this set provides increased defense while you are attacking, recovering from an attack, or charging an attack, while the armor allows you to resist interruption and knockback. Both make it less risky to try to finish a combo or charged attack when you're not quite certain of the distance or there's another enemy nearby.

Duelist's Coat: The Cap provides increased defense against enemies damaged with your last attack (within a few seconds); the Coat has increased defense when you are attacked from the front. Both protect you against the counter-attacks of your target, making it easier to finish off a single enemy, but leave you vulnerable to flanking.

Sniper's Studs: This armor set provides greater protection the farther away you are from an attacker, making distant turrets and other ranged enemies less of a threat.

Rogue's Robes: Each piece of this set provides greatly improved defense and status resistance against traps and environmental hazards. With the full set equipped, you can't completely ignore traps, but you'd probably willingly run through them if it gave you a tactical advantage (maybe 80-90% resistance).

Ambusher's Armor: This shadowy set reduces the maximum distance and angle at which enemies can "see" and track you, making it easier to sneak up on enemies or to get away from enemies that are chasing you.

Harrier's Hauberk: This armor set increases your movement speed, and provides increased defense while you are moving. Great for dodging attacks, flanking enemies, and other delicate maneuvering.