I've nearly always chosen Cass (despite her repititious dialogue) perhaps because of her red hair.
Anyway, when I 1st started using her, I'd give her an AMR, but she always managed to break and lose it.
Then one day I gave her the Medicine Stick with plenty of ammo, along with the Combat Armor re-inforced Mark II, or Riot Gear, and she became death walking.
I'd take her and ED-E to Quarry Junction and mostly sat back and watched the sh*t fly. Oh, they'd get knocked unconscious once or twice...usually by me using the AMR with explosive rounds just to get a few shots in, but those two would clear the whole Quarry themselves.
Plus, I rarely needed to repair the rifle or her armor, and she never once lost her weapon.
Though, I've yet to give her any whiskey. lol
Maybe that's why she's so deadly.
If we get into a big firefight with Fiends or whatever, I just tick her and ED-E for aggressive, let them do their thing, and go about my business looting bodies.
And I'm playing on VH.
When I'm on my own, I carry my trusty 12.7 SMG, a sniper rifle, and an AMR.
I also go into Lonesome Road right after leaving Goodsprings to get the Rioat Gear and the ED-E weapon-repair upgrade at no risk.
To sum up, Cass and ED-E are great bodyguards.