My barber uses a straight razor with a disposable blade and a new one each time. Your barber is what, like 90 years old?
How long would I have to wait to get tested? What if blood was on the applicator of the (nick a dab) he used on me to stop the bleeding? Would witchhazel thats I think is in the product be a disinfectant? Could blood dried or wet blood on the applicator transmit HIV or Hep also? It happened so fast!
It's hard to imagine the barber not cleaning his blade between shaves, not just for sanitary reasons, but to keep the blade sharp.
Yes, if there were blood from a person with hep C and if you were cut and that blood got into you, you could be infected. Chances are very very slim.
If you're worried go get tested and ease your mind.
BTW:HIV cannot be spread this way.