The ornamental design for handle for a mountainsportpole, as shown and described.
FIG. 1 is a front elevational view of a handle for a mountain sport pole showing my new design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a rear-left side perspective view thereof.
The broken line showings of pole and blade are included for the purpose of illustrating environmental structure and form no part of the claimed design.