User blog comment:Xilinoc/Ch. 555 - THE HERO/@comment-9096222-20131102093649/@comment-11051098-20131105222526

Do you mean the strange round thing that appeared when he stopped Bazz-B from attacking Haschwalth in chapter 543? I just checked it, and now I see it. It really does look like a portal which he just came out from.

As for the thing(s) on his left arm, it's only been referred to as an ornamental bracer, I don't know what it can be. But for creating portals as an ability, I would rather think the control of the portals would be done in his mind, not by an object attached to his arm.