Actually from discussions on IroWiki, Metaling Card dont work on Ranged Attacks. Which kinda makes sense.. coz, it says Strip Weapon lvl1. Lets examine the skill Divest Weapon?
A 5% chance of Autocasting Strip Weapon (which means.. even if it goes off; it is not 100% guaranteed it will Strip the Weapon off the target)
A 7% chance of Stripping the Weapon (Strip Weapon Lvl1; see below for complete formula)
Range: 1 cell
Just stand like 1 cell from the target, and it should work. If u are standing more than 1 cell away from the target, it should not work.
There is another thing with Strip Weapon. U need DEX!.... Sniper is a good choice, since its got lots of DEX. Formula
Success rate = 5 + 2 * Skill Level + (Your DEX - Enemy DEX) / 5
Conclusion: For it to work well.. u need a character who have High DEX, attack at close range and maybe high ASPD (to speed things up).