Fleuri Jodeau
Complying with Gerard's warning, ducked down as a spell came hurtling at them, striking the ground and exploding not far from Gerard. As the Hundi readied another attack in her hand, it was clear at this point that she was now done tossing magical hazards at the duo, and was now focusing on dealing with them.
If they did not react accordingly, they would quickly be removed from this challenge.
Fleuri was no mage, but he could deduce a few things based on what he saw from that first silver sphere. It was almost certainly a warning shot- a mage of such vast power wouldn't miss like that except on purpose, especially in what was explicitly meant as a challenge for the knights. Even in the unlikely event that its trajectory was a blunder on her part, she'd almost certainly correct her aim for the next one.
The most important detail is that the projectile exploded when it hit the ground, rather than bounce off or penetrate through.
If something hit it mid-air with enough force, that ought to make one of these projectiles explode prematurely, he reasoned. At least, he hoped that's how this worked. As Gerard grabbed some dirt, presumably either thinking the same thing or perhaps hoping to obscure himself, Fleuri pulled out the one object on him that he could use in for this purpose- his dagger. It wasn't exactly designed as throwing weapon, but in this instance he didn't need the blade to hit it.
For what it was worth, this ordeal of facing magic did give Fleuri some ideas as to where he wanted to go with his swordsmanship training. Between this and the fight in the Cazt tomb, it was clear that it wasn't enough to learn to deflect physical blades, he needed to learn to fight and deflect magic. He hoped that Rui- either the real one or the duplicate of this world- would be available and willing to instruct him on this path.
The moment that the Hundi fired a projectile as Fleuri, he'd fling the dagger in its path in an attempt to detonate it mid-air, then use the momentary concealment of the light of the explosion to move forward, weaving to the side to ensure that if another spell followed at the exact same trajectory, it would zip past him.