I answered the Tish sex question, so not sure what more I can say. It's in the walkthrough as I mentioned in my other post to you.
Knockout bombs are your friend (mostly) in this one. Use a knockout bomb when he pokes you in the eye and blinds* you. Give yourself a chance of putting him to sleep and to recover while he's out. The more he's knocked out, the more attacks you can get in without being hit back. One can guard too and decrease the damage, but I don't (just my gameplay style when fighting him). You can use Seed Means Life (healing skill mentioned above) to help restore some of your HP while he's sleeping. If you're at lvl 5 (603 HP) and have best equipment (The Breeder's Blade), as also mentioned above, you shouldn't lose all the time with save scumming (rng will eventually work in your favor). I'm assuming you saved somewhere right before the fight triggers.
I just finished fighting him (again) and beat him even when he double attacked me twice, was blinded twice, and one knockout bomb had no effect during the battle. I had no 'excellent hit' on him either. It was a great fight where the rng was pretty balanced for both combatants. There's really no special trick. There's only using what you have and finding a way to win the fight.
You also stated the 100 HP potion didn't work for you. I tried that in one of my fights and it worked for me. Went from 305 HP to 405 HP when I used it, so have no clue why it's not working for you.
A lot of us in here can take your save and get you past him, but you'll miss out on something because we can't save immediately after the fight unlike with the DD King. Just keep trying using all at your disposal and you'll win.
* - Game tells you if you are and when you can see again. You can land a hit on him while blinded, but it's sporadic obviously.
Side note: He's beatable with Vruk at lvl 4 too with just the short sword in event others playing and reading this need to know and find themselves in that situation. Tougher, yes. However, it's doable.