The moment that the elf using the rushing river style stepped in to his stance, Reese felt it. A pressure that he could sue as well. The unique pressure that came with mixing energy and the all around technique of swordsmanship. While it was not as unique as the sword aura that he had because of his spiritual and sword technique, it felt the same.
It might be considered odd for him to sense such a thing, but it was more instinctual than anything. Reese had grown up training the sword. He always trained with it. even when he didn't feel himself worthy to hold his partner as its weakest form.
But through the years, he had learned his family's technique. Learned the importance of a sword style and how it should be used along with his partner. The two had bonded when that day came. Learned from one another while also learning wh they were.
Creation is hard, cheer me up!