Out of all of the people to appear and save them in their current situation, they had never expected Russ to appear. Quite honestly, both Chris and Hikel had even forgotten somewhat that Russ was even with them, since they hadn't seen him in battle and were too concerned with their own fights.
The thing was, in this world, where Russ had no one to help him and no way out, he needed to help the only few that were on his side, he just wouldn't risk his life doing so, but having watched everything, he calculated it was better to have them alive than dead.
With the attack from Tenbris going in two directions, he needed to act fast, at the same time he didn't exactly know how strong the attack was, so the safest bet was to use the newly acquired sword he had with him.
Swinging it through the attack, it had done what it always did, and that was negate the attack, stopping it completely. After using the sword, he quickly placed it back in the scabbard.