New to the class and after doing a search within this forum, I have not located an explanation on how to fill a soul bottle. I can't drag it to a spot on the character sheet and throwing it onto the hotbar does nothing.
Also, once I have a bottle filled.. how do I use it? To be more accurate, do I use it when I don't already have souls accrued on my character?
You can drag it to your hotbar (make sure your hotbar isn't locked). You need 6 souls minimum, then just "use" the potion like you would use scroll of escape or anything like that. It should consume 6 souls you already have and lock 5 of them in the bottle. Later when in need you can just "use" the filled potion of souls to get the 5 souls back. Best use when you are already out of souls yeah, and need the quick powerup.
And no you don't need to have kamael specific weapon equipped in order to use it, only need to make sure you have at least 6 souls.