Oh Come on Mazzy is a shortling halfing you can crush her while you're walking
Minsc is a great 2-handed user also dual-wielder with mace/flail he's a undead slayer. Valygar goes is also a great dual-wielder deadly with katanas so you can use celestial fire. Yes he cant wear plate but there's magical st. leather armours and you can wear dragon armor. So there's no difference between a full plate and this armor.
But in your band, you need a Primary mage. Imoen is a great choice. Kick one of your fighters and go with Imoen. (3 melee fighters will be enough -keldo,valygar(minsc),anomen) Aerie is deadly with sling +5.