Board Thread:Episode Discussion/@comment-4141313-20181229081856/@comment-4141313-20190104191421

It is possible to steal something and not know how to use it.

For example, say I, a person with very little firearms experience, stole a tommygun from somewhere. Just because I stole it doesn't mean I know how to use it. I'd more than likely end up being shook around upon pulling the trigger from the rapid fire, and throw my shoulder out from the butt of the gun ramming into it on accident.

Let's translate that into Quirk's for the sake of comparison. When Midoriya was given One for All by All Might, even after training his body for several months, he wasn't able to use it properly due to lack of proper control, constantly firing off on 100% and breaking his extremities in the process. Only after talking to Gran Torino did he learn a smidge of control, and that only let him use about 5% at first, 20% currently. And as the lastest chapters

{SPOILERS for Anime Viewers and Manga Readers}

He still has no control as its gone beserk and releasing black tendrils everywhere, attacking both his teammates and the 1-B students, Midoriya even lamenting he thought he had finally gotten a handle on how to use One for All.

Now lets translate that into Semblances. Let's say Marcus stole a Schnee's Glyph Semblance. To start with, he wouldn't know how to summon anything, as Weiss and Winter had to train their Semblances to summon things. He also wouldn't know exactly what glyphs do what things, meaning he could fire off a Time Dilation Glyph when intending to use a Gravity Glyph.

Or lets say Marcus stole Emerald's semblance and tried to cast a hallucination on several people. He'd injure himself from doing it on too many people, seeing as two people gives Emerald a headache and nine people knocks her unconscious, and since Emerald needs to be concentrated and stationary so as to not disrupt the hallucination, he'd probably make it less authetic due to not knowing the limitations.

It's one thing to steal something, its another thing to know how to use it.