Marksman + assassin

i tried this build since 25 lvl so i have question to players who played longer than me
so... lets say im nuking someone from distance > enemy is in close range > here is question, can i use Foul Play from assassin tree?

you can use every skill from every tree, as long you wear the required weapons

its not that simple, it says that this skill doesnt require any kind of weapon but ........
last patch notes

Code:

* Expose Weakness: Now causes the enemy to take additional damage only from the Assassin’s physical attacks, not everyone’s.

so basically they limited this skill to assassin class only.

i think when you can use the skill and you have daggers, you can use 'Foul Play'
http://rift.zam.com/en/ability/1418517295/Foul-Play seems be a normal sin skill

Didn't expose weakness used to be a debuff on the mob for everyone who attacked it? From the wording of that i'd say it now means it's a debuff only the person who puts it up benefits from now, not the assassin skills only, but it's hard to tell without testing.

Exactly.