About Erwin skill "Take Aim"

    So here is the thing, I read about how defense penetration works in the "Soul Worker Mega Guide" and so far, (I'm level 51) whenever I use this buff, i have never noticed any changes on my damage. So i'm starting to wonder if the ennemies at my level have a too low defense for the buff to make a real difference.
    Is this buff really good? Will it become usefel later?

    Its useful against enemies with proper armor. Against basic mobs you won't see a lot, but trust me, the effect is there, its just subtle.


    Also keep in mind there's a large variance in damage you do between minimum and maximum attack, so that skews what you see by a lot.