When locked onto an enemy, throw the Tetsugen and press Up before hitting the target; the same can be done on the legs, except press Down.
Using The Tetsugen
Hit an enemy with the Tetsugen Blade and run around an obstacle. You will tie up the enemy and slash him with the wire. If you use the Fundo (the weight) to do this, the guard will get tied up on the obstacle. You can hang enemies with the Fundo not only from beams, but from ledges, boxes, or anything else that is higher than the enemy. Just tie him up with the Fundo and jump over the obstacle and pull the guard up. You can also just make him fall from a ledge, while he is tied up. To make it more fun, tie him by the legs and drop him from a ledge that goes into water. You can create more tension into the wire by circling it around corners or obstacles. This is useful when you are being pursued. Hit a guard with the Blade and run around a corner and yank on the Tetsugen.