That one for Vatnir actually seems interesting, especially with Slayer's Claw since it's an Axe and can benefit from the modal ability. The only problem I'm thinking of with this build is that I was going to give Slayer's Claw to Rekke as a paired weapon with Scoredo's Edge (was going to make a Rekke build similar to the one at the link below), but I could just as easily replace that with Tarn's Respite using its stacking -1 deflection on hit enchantment or with Min's Fortune for the stacking crit chance effect.
With Ydwin, my mind immediately went to Red Hand purely because of how strong it is. I wasn't planning on doing any Megabosses, but what's this Ancestor's Memory exploit your talking about?
That Konstanten + Fassina combo seems really strong in having two members of the party nuking enemies' Fortitude. Any recommendations on what Morning Star I should use with Konstanten? The only two-handed melee weapon I've ever really used with anyone has been Whispers of the Endless Paths.
That second idea for Mirke actually sounds pretty cool, especially with Mohorā Tanga's Harpooning enchantment to get the damage on it even higher.
Out of curiosity, would using the Whispers of the Wind ability with Whispers on the Endless Paths cause multiple targets to be hit due to WotEP's unique property to hit multiple enemies at once?
With Vatnir, wouldn't his Spiritual Weapons be kind of bad in comparison to normal weapons? From what I remember, Priest's Spirit Weapons become stronger the more they align with their god, but as Vatnir is not a player character wouldn't their strength be at the absolute minimum?