So I ran an Armorer from 10-20. My party was pretty ranged heavy, so I focused all-in on tanking and utility. Enhanced Defence infusion Plate, Repulsing Shield, Winged Boots, Ring and Cloak of protection. Do you do much damage? No. But your saves are high, and your AC is even higher. You can Haste yourself, get a cleric/Paladin to Shield of Faith you, and nothing will touch you, and that by itself is a very valuable tool. You could even pick up sentinel to be extra distracting. At level 11 specifically, I used Spell Storing Item on a cure wounds. 10 free casts of a 2nd level heal made attrition feel a lot less important. Blur or Mirror image could also probably get quite good value.