Karkat will just hope that Nitou's good enough to survive with the other supplies he's got. The guy has more than him even with the sickle gone, and they must be good enough with how little resistance he put up to lose this weapon.

"Kousuke Nitou," he repeats back, nodding. Then like a promise, "I'll see you around."

What happens then will be its own concern, but the end of the arena is still a ways off. He can afford to help his allies before then, and he's not about to backstab the guy who helped him this much.

After a look to check what's where, Karkat sets off. He's got someone to find, and time's not moving any slower.