Jack placed the long metal bar in his left hand perpendicularly to the monster's mouth, so the two ends of the bar touched the black shark's upper nose and its lower jaw. In this way, the shark's mouth couldn't reach him for as long as the bar held. He was instead pushed back following the shark's charge.
At the same time, Jack stabbed the knife in his other hand repeatedly into the shark's face. Damage numbers appeared but a glance at the shark's HP bar told Jack that this knife's damage was pitiful.
He accumulated mana manipulation into the knife and performed One-word Thrust. The martial art accurately hit one of the shark's six eyes. This wound finally caused it pain. It stopped its charge and swam away.
Jack took the reprieve and resumed swimming to the cage. Luckily, the shark's charge was slightly at an angle. The charge had pushed Jack further up and closer to the cage.