Jaune always knew his semblance, he just stopped using it. His semblance is actually very rare and ancient; that's why Phyrrah said his aura was strong. He first used it as a child and mastered it as the years passed, but one day he used it to the limit and almost hurt himself and his semblance.
"Jaune… Jaune… JAUNE!" he was brought back to reality with Nora violently shaking him. "They called us for the next round in the tournament. You and Phyrrah are going to represent the team in the next round!" she continued to scream.
"O-o-o-k-a-a-y-y stop sh-a-a-king and scr-e-e-aming." he could barely say. Nora suddenly stopped, but Jaune feel due to the momentum. He then got up and walked to the stadium with the rest of the team.
He and Phyrrah were facing off against Cardin and Sky, their stage was the beach and swamp. Before he could react Cardin hit Jaune into the swamp water and went for a flying tackle. Phyrrah would've went to help but Sky was distracting her, they've really improved. Carson had his semblance on his side; he could control, create, and shape slime from liquids around him.
He used this to his advantage and created a slime dragon that grabbed and crushed Jaune. Phyrrah couldn't even get away from Sky to help Jaune. Add the dragon went for the kill jaune screamed and his left hand began to envelop in a white light. In an instant the dragon dispersed and everyone was blown back, even the stadium descended a few feet before catching itself.
In place of the dragon Jaune was sitting on the shoulder of a big and white armored knight(think of the knight Zelda summons in super smash bros, but with a cape) his eyes closed and his hands clasped together still glowing. Everyone was shocked at this everyone even the teachers were surprised at this. Jaune's semblance is very ancient and very powerful, most robot soldiers are based off of them, Guardian knights.
"My word folks, I do believe that's a guardian knight." Oobleck commented. "Yes indeed, they are very ancient and powerful, it takes a powerful aura to summon one and a lot of it to keep it here for so long. Most people can only do sectional summon, only summoning one part."
"I'll do anything to protect my prince!" the knight said in a low gruff voice. "Why'd you have to use my pet name, it's so embarrassing." complained a flustered Jaune. The knight then rubbed Jaune's head compassionately.
"Remember that time when you first used your semblance, you were five and climbed a big tree, you fell and summoned me out of fear. I caught you and from then on made you my little prince, depth to protect you no matter what. You're strong too; holding my summon for a whole week, normal people can't hold a summon for a day." said the knight.
There was a collective awww, in the crowd. "Wait, as a five year old you were able to fully summon a knight and hold it for a month without damaging yourself?"asked Port "I remember a small headache, but other than that nothing." admitted Jaune.
Leaving Phyrrah Cardin and Sky went to strike Jaune but the knight caught them and the them out of the stadium. "Does that even count? There are three people." complained Cardin. "Well, Haos is a living physical manifestation of my aura, that's what a semblance is…. not the living part but yes it counts." Jaune smugly answered.
"And with a shocking knockout team JNPR wins and advanced to the next round." announced Port. Haos kneeled before Jaune taking his glowing hand into its own two. "My prince I was too slow in apprehending your assaulters, you must do what is right and reward me with punishment." the knight then got out an energy whip(like from fairy tail) and held it towards Jaune.
The whole stadium held mixed feelings towards them, most weirded out. "Haos I'm not going to punish you, you did a good job." Jaune reassured him. Haos then began hugging all over Jaune, "My prince is so merciful, anyway you must be hungry; let's get you something to eat." the Knight lifted Jaune to sit on his shoulder and walked him out of the stadium. Jaune was completely embarrassed by this.
"The archives never mentioned anything about knights being mother hens….., or their BDSM fetishes." said Oobleck. "You said that into the microphone old chap." commented Port. "Oh dear, I believe I did." admitted Oobleck.