[quote=@KatherinWinter]
[@Jinxlynx]Why just her left side
[/quote]

Well I did a shit job describing it but the arms is kinda like Thor's hammer Mjölnir in the way that it is quantum locked. She can lift and throw things without putting stress on the rest of her body, because when she picks it up her arm holds it in place without the effect of any other forces on it.
Also it acts as a way of balancing out just how ridiculous her power is.