Uhm...Vorpal IS a LP skill Travis. You are thinking the death touch assassin thing. Thats NOT what I am speaking of.YOU see it that way. I see it that vorpal (and rage) require SO MUCH concentration and focus you can't do anything else. Hense no charge up skills or life point skills.
If it were burst of will power, it would be a lifepoint skill.
I am usure where the cool down reference came from since I am not speaking about such skills.So look at it in the way - If you are under an effect like a "cooldown" or similar effect that would disallow potion use - just think of it as you are drinking the potion, but due to the stress on your body from whatever is affecting you the potion itself has no effect.
You can use Doug's reasoning for Poison, under a Cooldown you can think of your body as being so worn out that the potion cannot take effect.
Mechanics wise though a potion effect is considered a charged skill and cannot be used in conjunction with other skills. Now even though having a phys-rep gets rid of the charge time, a potion is still considered a charged skill.
First, no where does it say its considered a charged skill.
Second, the fact its considered a skill at all is what it so silly. Its a liquid, one that happens to have affects other than " aahhh thats refreshing!", but still a liquid...in a vial...that you drink.
Like I have said, I agree that during charge up time or at 0LP or less, not being able to drink a potion makes sense, its when its dissalowed during other skills/skill based activities that are essentialy passive once activated , that a potion isnt usable simply because its classafied as a skill. That essentialy means when the swashbuckler activates the vorpal skill, or a knight uses weapon focus, or someone uses hold groud your implying they are to "busy" to drink the potion. Thats just perposterous.