Right. Leather Armor AC is not fitting for her. It's weak, like she's a Rogue.
Minthara is a cleric. Clerics should, at very bare minimum, wear medium armor like Half Plate which is 15 + Dex, or if they want to go for stealth without disadvantage, they should give her, at least, a Breastplate which is 14 + Dex. Make it +1 at the very least, because she's a boss and so it is at least special in some regard so when you kill her you get some sort of cool armor.
OR, make it Light Armor but give it AC 15 + Dex so it's really cool armor and your rogues and warlocks can use it and get awesome AC. That would be cool. I could see her wearing a Leather Armor with specialized high AC that equals medium armor AC, but not Leather at 12 AC. That's super lame and virtually worthless.
Leather 12 AC is like "Yes! I killed a boss. Let's see what she has. What! AC12 Leather! Pshh! Lae'zel wears half plate and my MC can wear Scale +1 and Shadowheart can wear Scale +1 too, and that's WAY better, and I got that as soon as I got to the grove. Minthara is lame. Her equipment sucks and isn't hardly worth picking up."
