It's not exactly like he was trying to hide it, and though Shun would've preferred to keep it to when the fight actually starts, he's not so proud that he'll not draw his weapon just because he's being told to. So after no more than a moment's pause, he draws the knife into a reverse grip in his hand.

"If it'll make you shut up and fight me already. You've wasted enough time."

He's taking the fight seriously, as he always does, but the lack of actual action on the other's part is getting rather annoying.