Seron didn't need any combat technique, as his quantum bracelet was already filled with hundreds of techniques that he had received from his family. It was only his weak mana core rank that prevented him from learning and mastering them.
But for Jason it was entirely different, he only had tierless foundation techniques, an all-rounder tier-1 weaponry knight technique, and the only special technique he had was weightless steps.
As of now, Jason could only use Tier-1 techniques in a fight that would go on for a longer duration without injuring himself. That had been the very reason for him to pick two particular Tier-1 techniques in the beginning.
[Transience Strike] was a Tier-1 technique, as the name suggested, focused on a single strike, to kill one's enemy without much effort.
[Hazardous-Assassin] was another Tier-1 technique with multiple sequences used to deal heavy strikes at the enemy with two daggers.