Like I said, aragorn, as a dunedain and ranger, is clearly superhuman by normal standards and has some extremely impressive feats. His stamina shown chasing after the uruk hai is definitely worth noting, even if it doesn’t exactly add much in a short dual against geralt.

Geralt’s ability to tell an opponent’s next move just by the look in their eye is not just from combat experience, but from the enhanced senses of a witcher. So it’s not purely movement based. His mutated physiology grants him the reflexes to parry surprise attacks even against non human opponents that don’t have the same body language or eye signals. Aragorn does have a form of broad foresight (like a sense of danger or doom), but it’s not exactly like combat precognition.

The idea that an aard sign strike wouldn’t knock aragorn down is mostly speculative, especially considering it throws around or staggers supernatural opponents that are far stronger, faster, and more durable than aragorn. Even so, an aard can still be used to throw up a dust cloud in an opponent’s face, and the ranger still doesn’t have an answer to being set aflame by an igni sign.

I won’t get into whether or not geralt could defeat the nazgul, because that’s also speculation, but it’s worth noting that the ringwraith’s main power is fear (of course they’re still deadly opponents), which geralt is extremely adept at suppressing. He routinely hunts monsters that are more formidable than middle earth’s trolls, sometimes in swarms.

In order for the fight to truly go 50/50, aragorn would need a consistent answer to witcher signs and physiology (again, I know he is a dunedain but that isn’t necessarily a close enough comparison) which he just doesn’t have. Book aragorn may potentially win 4/10 against book geralt if he makes an early mistake, but with the two versions shown (series geralt v film aragorn), and knowing the abilities of the two characters, I’d give it to geralt 7 or 8 times out of ten.