[Jim McDougall]

As previously noted, the quasi military frontier police formed by Diaz in the 1860s, the 'Rurales' while heavily armed with revolvers and carbines, still wore cavalry type sabers (typically) through the late 19th c. and certainly into the 20th. What actual use of these took place is hard to say, as accounts of combats, battles etc. simply presume use of guns, and seldom specify if use of sword(s) was part of any action.

The cavalry sabers were typically of the three bar hilt form familiar from US Civil War examples from the M1840, M1860 types. These often had blades marked A.C., which while often presumed to mean 'armeria centrale' for the Mexico City armory, it is suggested these were the initials of Acier Colubuzier, who held the monopoly on imported swords into Mexico.

Often there are the RM stamps representing Republic of Mexico.

While these were used of course from 1870s onward, swords, like most arms in Mexico, remained in use for decades if not generations.
This example reflects the rugged condition from such years of use on the frontier, and the hilt is misshapen possibly from being trampled by a horse?
There is a centavo (date obscured) hammered onto the pommel, perhaps a good luck amulet? or simply decoration.

Note: There are numbers of three bar hilt sabers of British M1821 form which have turned up in Mexican context, usually with an oval cartouche with PDL, Luneschloss of Solingen.