Sources for gladius hilt materials

[Jesper D]

Hey!
Regarding gladius hilts... Some pretty basic qs.
As I understand it no hilts have survived?
Thus organic materials are presumed? But are there any evidence of what
organic materials were used? Is there any basis for the so common two tone wood and bone combo?
No mention of metal hilts being used at all?

Also why would anyone want a bare wood, metal or bone grip when there was leather, which I
understand to be a much more reliable and very accessible gripping material.

Cheers,
Jesper