Since this is the first time I have the chance to speak with other Witchaven fans, I will do this question that has been haunting me for twenty years.
The manual of the game clearly states that starting with level 4, you can dual wield both the dagger and the broadsword. The problem is... I don't know how. The manual doesn't explain how. Even ETTgrinder mechanics' page doesn't explain how. I tried every key in the keyboard and a lot of key combinations. And it has been haunting me since I was a kid (as much as those freaking jumpscaring ghosts).
So... any thoughts?

www.youtube.com/watch?v=083x4Iy-eRg&ab_channel=Civvie11

It's been a while since I watched this video, but I seem to remember civvie mentioning that you can dual wield, but you can't choose the second weapon you wield.

If you have 20 minutes to spare... civvie is always entertaining.

I don't think you can choose, As far as I remember it triggers automatically, and allows you to use the dagger or morning star (if you have it) with any other one handed weapon, as long as you're not using the shield.

Yes, when you use the longsword/broad sword (weapon slot 5) the game will use one of the lesser weapons, prioritizing the morning star, never checked if it used the short sword or dagger) if your left hand is free.
It's more of a gimmick than a full feature, but it's kinda fun.

On the original DOS version, with basic controls, S raises or stashes the shield in WH2.
In WH1 you have to wait until the shield is broken to dual wield again.