Thank you all for your interesting comments.
I'm of the opinion that the name is a bit longer - I see it as Monterroza (acc to
https://forebears.io/surnames/monterroza - it is found mainly in Colombia).
The frog is attached to the sheath with many miniature nails, yet it holds firmly. The typeface seems older to me (I would guess that's how my grandfather wrote), so I think from the way the scabbard might be circa 1950s (?).