I appreciate that Geralt will have prepared himself for the fight, but an hour is a long time to hold out against an opponent whos stamina and regen don'r rely on limited resources. I also find it hard to imagine that Akaza would let up for a moment to give Geralt a chance to reapply his oils/potions. If we were talking about a fight that lasts 10-20 minutes I would absolutely give this to Geralt's prep, but 1 hour is a long time to be fighting nonstop.
You severely underestimating the fighting endurance witchers in general have.
Geralt himself managed to fight a striga for an entire night until dawn set in. Although half-way through the night Geralt sealed himself in the tomb which striga resided which lifted her curse so it half counts. Even discarding that we have Witcher George who we can scale to Geralt considering that physically there isn't any other witcher (aside from Letho) than compares to Geralt due to the further mutations he's experienced. Witcher George was a witcher that fought a Green Dragon for an entire day and night cycle with not even a proper silver sword but a steel sword which blunts itself on the scales of dragons and he managed to slay the dragon while being literally at deaths door. So an hour of fighting isn't something that would Phase a prepared Geralt and especially when he has prior knowledge on demons.
There is actually a correct assumption that potions don't really last for a long time, especially ones like Blizzard which gives Geralt an exponential speed boost but for a short period of time. Only potion that would last Geralt an hour or more is Tawny Owl which coincidentally boosts the stamina regeneration but because Geralt has prior knowledge on demons he won't be relying on potions but decoctions instead which actually last for more than day and have a considerably greater effect than potions at the cost having greater toxicity and only being able to use two or three (but in this case it actually helps as it boosts the attack power of Geralt). Succubus and Wyvern decoctions make Geralt gain considerably more power throughout the fight while the troll decoction enhances his regeneration capabilities for a prolonged period of time.
The best choice for Geralt to counter-fight demons like Akaza is with his best sword, Aerondight, which amplifies it's power considerably on each hit which can accumulate on one massive strike with the effect of setting the opponent on fire. And if I read Akaza's weakensses correctly, he is apparently weak to a plant called
Wisteria. Why I bring it up is because it is also otherwise known as G
licynia which witchers at kaer morhen most likely have in possession and can create an alchemy oil to counter-fight and considering this fight is taking place in kaer morhen where there is a massive storage of artifacts and rare items it can come in handy for Geralt to use.
As for signs, Quen is THE sign that will keep Geralt alive throughout the fight. Quen is straight up busted as a protection spell as it can protect Geralt from attacks FAR outside of his weight class and be able to reflect 50% of the energy back to the attacker which is fortunate as it is the biggest counter to the Compass Needle in both forms. In the first form Geralt can counter-attack Akaza without taking any damage, while in the second form it is the single biggest
"No u" ability that isn't capable of even being breached. Igni comes as a loose second as it can hinder regenerative capabilities of demons somewhat, this is considering that Igni is capable of setting ablaze higher vampires who similarly have a regenerative capabilities and resistance to fire.
All in all does Geralt beat Akaza in a straight up fight?
No. He does not.
Despite all I said, Akaza has more experience than Geralt (133 years vs 99 years) and he is physically stronger, has more busted techniques and Geralt has no way of physically putting him down, even if he possessed dark blades.
Now, it is an entirely different matter if it is about waiting till dawn as Geralt will 100% take advantage of any weakness present and considering he has prep time and prior knowledge he'll intentionally drag out the fight like he did with the striga only attacking in key moments and only holding off Akaza.
Normally, if this was a standard fight where the night didn't end and no one had prep I'd give to Akaza low-diff while with the thread rules Geralt takes this Mid to High-Diff