Might just be rng but the armor selection for Garrison seems incredibly poor. While the armor for the others seems to scale to level, the best I’ve gotten for Garrison is level 5 paladin armor.
I have been running around with an epic Hilltop something (lvl6) for a long time. Recently I found a rare Slime-encrusted Coat (lvl13) with the enchantment Magic Resistance which counters the item’s poor Magic Def.
His best armor i think can be found in the sewers missions or in the arena rewards. It’s a lvl 11 Berzerker Armor, until they have the official release that’s his best option. Even better than an epic Slime Encrusted.