The ornamental design for a shieldattachment for a headworn visor, as shown and described.
FIG. 1 is a front perspective view of a shield attachment for a headworn visor showing my new design.
FIG. 2 is a front elevational view thereof.
FIG. 3 is a rear elevational view thereof.
FIG. 4 is a left side elevational view thereof, the right side being a mirror image.
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom view thereof.
The headwear outlined by broken lines in FIG. 1 depicts the environment of the shield attachment for a headworn visor and forms no part of the claimed design.