In addition to the flexing, see if dodging skills allow you to perform a back-flip for maximum assertion of dominance over the gaurd.
You are a legendary dodger. Of course you can do a backflip. You flex on that guard.
"Bravo, bravo.", he says. He pulls you, the other dwarf and the goblin into a huddle.
He continues, "We are going to make such a good team. Are you ready to conquer those monsters?"
The goblin squirms out of the huddle. She says, "I will do what I must to survive even if that means being entertainment for you filthy dwarves."
The other dwarf says, "Please, I just want to go back to my family."
The goblin replies, "At least you get to go free after the fight, and you, champion, why would you volunteer to fight in the pits?"
"for death and glory of course. Now, little one, we have to get you ready for the fight. Would you like to spend our time sparring or in the danger room?"
You use hand gestures to convey the idea of sparing in the danger room.
"What a novel idea." the champion says. "We will get you in shape in no time!" You and the champion squeeze into the danger room together.
You are pelted by wooden spikes but they mostly bounce off your armor. You don't take any injury beyond light bruising. You and the champion wrestle for over an hour bringing you to competant wrestler status. More impressively, you shoot up to professional armor user.
"Times up." A guard says. You and the other gladiators are led down a series of tunnels ending in a large copper wall and a weapon rack. The weapons on the rack are steel and of decent quality.