There is no known explanation regarding these different shaped bolsters, and their geographical distribution, except that the rounded bolster (“button”) seems to be of earlier appearance.
Typical Uruguayan and Brazilian button with sheat provided with a “botton keeper”
16.
17.
Because of the use of a bolster, puñales never have any type of guard or crossguard.
Squared Buttons
18.
19.
Trade Marks
20.