Till now I try to compare my effort with main character of mine who is pretty dope - 2handed war/barb angel.
Alsi I'd like to inform that my current game stage is a mid game -lvl 13
So far I've tested two builds:

Vivi + Sword Saint + duelist - 1/8/4,
result was meh, low dps, high armor and only two attacks per round - pethetic. I took some points into dueling sword and tried to make this char a crit machine, but still it doesn't feel some op as expected.

Mutagen warrior + Eldritch Scoundrel + duelist - 3/5/5
The idea was to parry the attacks and counter them with sneak attacks, yet I think it does not work. Funny enough with selfbuffed mage armor I've reached even higher AC then in previous build.

This time I've reached to 3 attacks per round, but still dmg was not that great as expected.

Plese, share your ideas, lets make our own witcher!

Br

Maybe just pure class mutagen warrior? Just lots of stat increaes so you can hit with your greatsword while doding.

issue with pure warrior is that it lacks of AC later on in the game - keep in mind that wither use light/medium armor
also he uses signs in order to deal with magic, some sneak attacks are also much apriciated

I don't know
Alchemist get Mutagen and Spells.

So Maybe the other levels in 2H Fighter as main class?