@Icelord888 Go into the database, select the states tab, create a new state called "poisoned blades", double-click an empty line under traits, select the attack tab, select attack state, select Poison on the drop down menu, and adjust the + field to reflect the increased probability of inflicting Poison when your character is affected by "poisoned blades". Now go to skills and create a skill called "Apply poison", set scope to The User, change hit type to Certain Hit, double-click an empty line under Effects, select the State tab, select Add State, select "poisoned blades" on the drop down menu, and make sure it's at 100%. Now you can test it, but I'm relatively certain the skill will apply the "empowering" state to the user and the user will then have the added chance for the "inflicting" state, as set up, for the duration of time the "poisoned blades" state remains on the user (which you can set as desired). Of course, this just uses your example, but you can change the names of the skill, the "empowering state", and the "inflicting" state to suit your needs.
EDIT: I double-checked that Attack State does what I thought. There's apparently one more thing needed to make it work. You need to give "Apply poison" the effect of add state:normal attack, according to this quote I found of
@caethyril ...
"Skills with an
Add State: Normal Attack trait will add any "attack states" at the specified chances.
To specify a new attack state, just add an
Attack State trait to a relevant object. In this case, add one to your weapon to make it contribute Paralyse with 30% success rate: double-click an empty row in the weapon's trait list, and you'll find Attack State on the Attack tab.

"
As you can see...they were working on applying an inflict paralyze state to a weapon in that thread, so...pretty much the same. Oh, and yeah, one other thing to add as mentioned here, you could set the "poisoned blade" state on the weapon itself instead of the user, so only attacks with the actually "poisoned blade" would have the chance to inflict poison. Otherwise, the user could use a club and since they would have the state on their self, it would be like the club was poisoned too...kind of misapplying the effect.