Question on Defense/Resistance

[OGKingsBounty92]

What's so good about the Leather Dress with 5% Resistance as opposed to plain Defense stats? For example I have a stack of Horsemen with 55 defense and with the Advisor's Dress they get 57 due to the +2 of the dress..if I switch to the Leather Dress I lose the +2 defense and see no stat increase with the 5% resistance. Is there something I'm not seeing with the Leather Dress 5% resistance? Which is better to have since I can only equip one of them at a time?

[Petwin]

When you place your cursor on the defence of a stack (the number I mean) you see a window that states the resistances of the stack versus 4 kinds of damage (physical, poison, magic, fire). A 50% resistance means damage taken is halved. You can increase those resistances up to 95% with the right items.