In Jihaku, GACKT’s autobiography, he discusses his apparently incredible talent in karate. He also mentions that, in his youth, he was a bit rough around the edges, and one of the mediums he used to express this was through ending up in knife-fights. (He also stated, quite gruesomely, that when he had outgrown these antics, he took a knife and cut off the scars from those fights.) GACKT is still renowned as a collector of knives.
In any case, if you ever wanted to see any of these talents in action (as well as for any of those who ever wanted to see GACKT kick a punker chick in the face), the PV to The Next Decade (theme song to the Kamen Rider vs. Dai-Shocker movie that hit Japanese cinemas in August) is for you!