The ornamental design for a blade for a divingfin, as shown and described.
FIG. 1 is a front perspective view of a blade for a diving fin in accordance with the present invention;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a right side plan view thereof;
FIG. 6 is a left side plan view thereof;
FIG. 7 is a front plan view thereof; and,
FIG. 8 is a rear plan view thereof.
In the Figures, the broken line showing of a foot receptacle of a diving fin is for the purpose of illustrating environmental structure and forms no part of the claimed design.