I'm currently restoring one that had the exact same handle as the OPs. Mine has a Diston-Diston medallion to my inexperienced eye looks like it is made from steel. The handle was cracked (and I didn't like the look+feel of it anyway) so I'm making a new handle for it. The stamp on the heel says it's 4 1/2 ppi.

Incidentally, while on the subject of medallions I saw this saw in the Coolgardie Museum a few weeks ago. I'd say the Diston-Diston medallion and the blade are original but I'm pretty confident the handle is a replacement.