Defence makes you harder to hit and resisrance makes you take less damage.
Other way around, resist lowers the damage, defence is like a dodge.
I wouldn't bother slotting the resist - S/L defence (very common damage types) is better than the Fire/Cold resist (cold is very uncommon, fire, uncommon-ish).
IN MEMORIUM OF GAYBABY
CRUELY TAKEN FROM THIS WORLD WHILE SO YOUNG
Trust me to get them the wrong way round. 
Thanks guys, good point about the resist off the top of my head can only think of crey that use ice and outcast who I cant say I have seen in COV.
The Good Guys
Miss Marvellous, Hot Stuff, Seduction, Killer Watt, Serenity
The Baddies
Lady Malevolant, Sea Nymph, Sweet Psycotic, Glacial Tigress, Queen Nerferta
I think these powers are pretty much like the ice tank powers anyway. Both shields prob grant a whopping cold resistance so if you have them both you can get pretty close to the cap anyway (which is almost never useful). The fire resistance is prob fairly minor and not worth slotting. Put +def in these shields.
I really should do something about this signature.
Just started a ice blast/Cold Domination
I have noticed that I can slot this shield with defense buffs and resist damage. Am I correct in thinking the Defense buff lowers the damage taken should a hit land and the resist damage make the target harder to hit.
Thanks in advance.
The Good Guys
Miss Marvellous, Hot Stuff, Seduction, Killer Watt, Serenity
The Baddies
Lady Malevolant, Sea Nymph, Sweet Psycotic, Glacial Tigress, Queen Nerferta