Van has had the ability to control the flow of things since he was a child. Controlling flow means that he use he bodies energy to slow or speed up an unbroken line of something. Currently he can only use his power to slow down the chakra flow of his enemies and speed up the chakra flow of his allies. When someone's flow of chakra is slowed down is has the affect of making them weaker than their average performance. This affect is vice-versa with speed ups as it allows more chakra to run through the body causing the affected person to become stronger than they normally are. Due to no one of his knowledge having this ability yet, it is not as fully developed as it could be, as it could be used to control more than chakra. Currently his power can only lower an enemies power to 80% of their base and he can cause his allies to go up to 120% of their base. The fault of his power is that it uses a lot of power to use, so currently he can't keep it on for a long time.
Van can use his power on himself and an enemy at the same time in a one on one fight, but the real beauty of his power comes from his allies. Depending on the number of people fighting on Van's side at the time of a battle he can keep his power going longer and stronger than just him alone. On the flip side Van can use his power on more than enemy, but the reduction it does because its spread out is so small that Van wouldn't waste time on using it on more than one enemy at a time.
Van's power is a great balance for him because he is mostly a close combat fighter, choosing to fight with his sword. His power allows him to slow down the fastest enemies so that he can on par with their speed. He can lower the strength of his stronger opponents so that his blade will not break on contact of impact. Only if he were with someone else or if he will was higher level could he easily take down his opponents will ease of skill, but then being high level or having an ally would already put the battle in favor.
Van's ability with a blade it what sets him apart from others. He uses a saber type weapon to parry and quickly return with an attack (think of Marth from Fire Emblem). He has a lot of agility in close combat and can easily move about in the closes of quarters. Through the use of different stances he can cause a large amount of damage capable of more than his body can normally deliver. If his sword is knocked from his hand, he doesn't fret because he is also very efficient at hand to hand, mixing different styles he learned in school, but he feels the most natural with a blade in his hand.
Van's country also knew how to use summoning techniques similar to the one's in this land. Therefore, he himself has some secret summons that have been passed down to him from his bloodline. He never learned the basic ninja techniques in his school, but in the time he has traveled he learned the basics from various religious temples. So far he can us substitution and clone techniques and since he has an earth chakra he can use rocks to block his enemies attacks.