If they are jumping, they are most likely going for distance, which means they are in movement the entire time, which makes aiming signifigantly harder. And they can still run quite fast, and only need to land one blow to incapacitate a Mistborn to the point where the Unoathed could kill them or just kill them.
I think that the Mistborn has the incredible power to evade, but the Unoathed is incredibly powerful. Just as First of the Tide said,
The Unoathed can rearange, so assuming that it is one duralumin-steel shot to completely break a piece (which is incredibly unlikely, most likely 2-4), then our Mistborn would need constant replenishing of duralumin and steel, depending on what you mean by 'sufficient' metal reserves. Throughout this whole battle, the shardbearer is chasing the mistborn down, and has a good likely hood of getting at least slightly close.
I do think that the mistborn can evade, but the shardbearer can also survive. For much longer than the Mistborn can burn.
Also, perfect knowledge is a stretch.
Also, I found this. I would assume this means that the mistborn has, say 3, extra vials full of allomantic reserves, and not much more. That doesn't give much time for the mistborn to hurt the shardbearer.
I back the Unoathed here.