"The basement," Zuko said simply and pushed off of the wall, turning on his heel to head in that direction. Once to the door, he waited until Katara had reached it as well, then held it open for her, being that her arms were full of weapons that she could hurt herself with if she made a wrong move.
Once down there, Zuko motioned to a table, "You can set them there. We'll start with the crossbow."
Normally in training situations like so, he'd remove his shirt, but given their past experience with him being shirtless? That was a very bad idea. He'd just deal with it being sweat-soaked.