Board Thread:Off Topic/@comment-27425734-20170826213348/@comment-27447621-20170920185344

The thing that instantly comes to mind is a Telescoping blade. Each part of the blade slots neatly inside the part below until it tucks into that intersection between the hilt and the top of the handle.

That's one idea at least.

Also, for the third form, the hilt looks like it'd get in the way, maybe it could fold or telescope as well.