While not a bad poster, I do wonder why Wolverine would need a Katana?
Let's see... his blades are at best 10 inches long, conservatively probably 8-9 inches. A katana averages 28-30 inches. So, I would guess he wants to use a katana for reach, as it is 3 to 4 times longer than his built in blades. On top of which, if he doesn't want to show his little trick, he needs a weapon. Why not the weapon of choice of his enemies in this story? It isn't that hard to justify.