Creed's sword, Kotetsu, used to just be a normal shanking sword, but it underwent some enhancements. As you can see,
the blade is invisible, nor does it have a
solid shape. So even if you're
80 meters away from him, he can still hit you. No room for running, I'm afraid. ♥
See Creed
whip out his weapon. See Creed
pwn a helicopter.
However, the
hilt of Creed's sword is still visible. Thing is, you can't tell
how long it's going to be, since it was mentioned previously that it has no solid shape, and at the same time
he can manipulate its length.
As for its special abilities, not much. However, the Imagine Blade has its levels. Level one, two, three, and max. Since Creed is from early on, there is no level three, or max yet, but he's already reached level two. Also, it's made up of Creed's ki, aaaand it's a godmodder sword. :'D
Some characters in the series don't refer to it as the Imagine Blade though, but they just call it the Invisible Blade/Sword/whatever. :'D