I gave Ian a hunting rifle and ammo to go with it and told to "use your most powerful weapon on the next battle", but he still uses his 10 mm pistol. If I take away his 10 mm ammo, he just fights unarmed. And there doesn't seem to be any option to make him wear better armor at all.
What to do? What are the limitations? What equipment will companions use, if I give it to them?
Bonus: Dogmeat can't use any gear. Any way to make him tougher?
Best Answer
Ian specifically can only use knives, pistols, and SMGs. I believe that's hard-coded into his AI.
Dogmeat can not be given any gear to use except Stimpaks, as he is a dog.
Sources:
http://fallout.wikia.com/wiki/Ian_%28Fallout%29#Notes
http://fallout.wikia.com/wiki/Dogmeat_%28Fallout%29#Notes