Of course, you want the player to start with a weak weapon and low ammo and slowly work their way up. I just wish the game gave some sort of explanation for it so we aren't left with the (correct) impression that Chris is an idiot working for even bigger idiots. Although to be fair, you and Sheva get ten bullets each, so you've got that going for you.
A companion is a tricky proposition for a game designer. Make her too weak, and the player will hate her for slowing him down and being a burden. Make her too strong, and the player will hate her for stealing their kills and ruining all the fun.
In any other game I think she would have been a fun teammate. She helps you, she picks up stuff for you, she stays out of your line of fire and tends to do an admirable job (for an AI) at covering the openings you aren't. But this is a Resident Evil game and thus combat often revolves around ammo conservation, which is very complex business and not something modern AI is able to do skillfully. (Yet.) Which means that the balancing point between "burden" and "kill-stealer" is going to be extremely narrow.
Sheva ends up being a burden because she aims for the torso and doesn't move to finish off zombies with melee. One good stomp can kill a zombie that's been knocked down but instead she'll stand two paces away and plink away at its torso, thus wasting her time and about eight bullets.