I first soulbound the Marux Amanth dagger to my Paladin/Priest main under PALADIN.  I could not cast Flames of devotion.  I severed and re-soulbound as PRIEST and did't have any problems.

 

I severed the soulbind and re-soulbound on Mirke as Shadowdancer under ROGUE.  I could not use rogue abilities or some monk abilities.  When I was auto attacking, I could not see the dagger in my off-hand on Mirke's character.  The only way I could use all abilities on Mirke was to single hand the dagger.  I tried it in main hand and off hand, with sabre and dagger and stilleto as the 2nd weapon.  It was mostly melee abilities I could not target, but I also could not cast the Rogue's Escape ability, which doesn't require a target.  I could cast the Monk's Flagellants Path ability, which does require a target.

Edited July 1, 20187 yr by Ger

After some testing, this only seems to be a problem when I have copied the dagger into a second weapon slot on Mirke.  If I only have it in one weapon slot as main or second hand, I have no issues.

 

I went back to test on a previous save when I main had it soulbound as Priest.  Copying it to a second weapon slot caused no issues that I could tell, but the only real melee ability I could test was Flames of Devotion.  I tried both fully upgraded soulbound and before it was fully upgraded.

 

Another aspect that may have caused the problem.  I have the Fleshmender armor, which can be enchanted to give the wearer another weapon slot.  I tried to equip a couple of flails in the 3rd slot and 3 times I opened up my inventory and the flails were shunted back into Mirke's personal inventory instead of equipped in the extra weapon slot given by the armor.

 

Really, I have no clue what caused the issues, I've just found a way to work around them.

Edited July 2, 20187 yr by Ger