See I don't care about duration, I want to know if WTP will decrease the opponents so that in turn it can effect higher level opponents.
It would be nice to drop a max'd out "weakness to Poison" while slowed on an unsuspecting "Chief" perhaps a -65%, and then follow up with a fully buffed (5 pieces of alchemy enchanted gear (rp my lab gear)) and see him go nuts on his weaker buddies.
The alternative is pick pocketing a frenzy potion into a weaker bandit and then popping an invisibility pot.
Found the answer on the UESP: Target is % weaker to poison for seconds.
Weakness to Poison has to be applied prior to a dose of poison for the weakness to take effect. For example, if the enemy is not weakened and you use a poison withWeakness to Poison and damage, the damage will not be affected by the weakness that time but the enemy will be affected in later uses of the poison.