Without Andre you can't upgrade basic weapons to their certain advanced versions. Not a big deal imho (because they're shit anyway compared to some drops and you upgrade those special drops at bonfire), but some people probably would say it's restart-worthy.
BTW. Bloody hell, Sif fight is annoying without a shield. Killed her on something like 7th attempt on NG+, I'm still not 100% sure what are the tells for various attacks to dodge them reliably.