based off of wiki weapons have a chance of getting one of three variants outside the normal reduced charge time gained at level 5 and 10 (increased attack speed, reduced charge time, or damage bonus to a certain family of monster

for armor:Bonus damage protection from (one form of damage), Bonus status resistance (one condition)

http://wiki.spiralknights.com/Unique_variant

basically my idea is to add a few more variants:
for weapons that dont innately have a condition add a variant that gives a minor chance of a certain status

example: upgrading Calibur to Tempered Calibur could give you the Unique Variant: "Good chance of causing Minor STUN"

now i know what you're think "What if i want to upgrade it to a Cold Iron Craver? Would i get both stun and high damage to undead?"

i am unsure on the whole "inheritance of unique variant effects to weapon WITH an innate effect". i assume that you could transfer the effect of stun over to CIC while CIC loses its high damage to undead.

for armor:

including increased damage protection from a form of damage like Shadow and Piercing, add "Increased damage protection from (Insert monster family name here): low"

so a Tenderfoot Thwacker does normal damage and a Tenderfoot Scorcher does elemental damage but both are of the Gremlin monster family so armor with the protection against the Gremlins would work here

for shields only: Shield Health + (some amount)

essentially this means you can block more