What if this was a sword fight only? Geralt is faster but Aragorn is bigger (he’s supposed to be like 6’ 6”) and most likely stronger.
Also it’s worth mentioning that Aragorn was able to deflect a thrown knife from Lurtz and dodge arrows in Moria. Obviously blocking a crossbow bolt from close range is more impressive, but still, Geralt’s speed advantage might not be that much. But on the other hand, Aragorn’s strength advantage might not be much either. Idk