I think the red aura in tales of graces had a similar effect, and all you had to do was guard for almost 2 seconds. In Tales of Xillia 2 you actually have to equip each might charge skill for the effect to even occur. There's 3 of them and the second one guarantees applying weakness damage. So yeah, it can be considered a cheap skill, especially if a character has a weapon that can attack multiple weaknesses in a single attack.