I have some question smirk

In earlier times I used the skill "Poison Weapon" and I found it a great skill, but now I can't find out HOW I must use this skill! smirk
I have some poisonflasks in my inventory, the "Poison Weapon" skill is "active", but what now?

Must I rightclic on a weapon or leftclic? Must I clic on the skill-icon when draw a weapon I wish to poison? ... ?

I try different things out, but nothing happens and I did it earlier with the same game-install, so I know it isn't a bug ...

Thanks in advance wink

On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin,
it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !