Curious if setting a companions attack preferences (ranged or melee) could weaken the character as far as battle effectiveness goes.

I.E, if I set the Brotherhood Scribe companion, who claims to be an Unarmed specialist, to Ranged stance so she's less likely to die, would her effectiveness in a fight drop drastically, or does she have the necessary skills to still be of use with a gun?

Being Brotherhood she should be trained well enough to use an energy weapon. I just let her stay unarmed, upgrade the armor and toss in a grenade rifle. Ration out the 40mm grenades carefully to her by keeping most in ED-E and letting her have them in batches of 4-6 between fights.

So in your experience, by giving her a ranged weapon despite her unarmed specialty she can still hit things from afar with decent enough accuracy?

She switched to a ranged weapon on me without my telling her to do so. I gave her an incinerator to carry and she started to use it. I was surprised because I assumed since we had the companion wheel with the choice of ranged/melee that the devs had fixed the problem with followers dropping out of melee (even though unarmed isn't melee) that was present in FO3. Anyway, it still seems to be a problem and she changed weapons (probably based on the DPS of the weapon) and she did great with it; or was at least adequate. If you are going to give her something I'd say EW since she is tagged in it. Doesn't she come with some kind of ranged weapon? I always had her set to use her Power Fist because she was so great with it. She moans and groans about it but her skills are at 76 in EW v. 103 in Unarmed. She can handle herself with a ranged weapon.

Much obliged, Llama. Thanks for the info.