His first instinct would have been to retaliate with his fists like usual since the use of artifacts was forbidden and Uriel did not have any offensive skills. That condition alone set the table for unfair fights all over since his trait was directly related to the use of weapons and it made him ponder if Tina made the rules of the tournament specifically to target him, but that held little importance to Uriel as he now was forced to go back to his origin and use his most reliable weapon which was his brain.
The first thing he did was to pretend he was going for an offensive stance which prompted all the enemies to merge by the doctor's side in order to protect him. If the doctor fell, his trait would be deactivated and the wounds on Uriel's body would stop festering on the spot. That was something they wanted to avoid at all costs and Uriel knew it.