The ornamental design for a finger-splinting sheath device, as shown and described.
FIG. 1 is a first perspective view of a finger-splinting sheath device;
FIG. 2 is a second perspective view of the finger-splinting sheath device;
FIG. 3 is a front view of the finger-splinting sheath device;
FIG. 4 is a left-side view of the finger-splinting sheath device;
FIG. 5 is a top view of the finger-splinting sheath device; and,
FIG. 6 is a bottom view of the finger-splinting sheath device.
The finger-splinting sheath device is symmetrical, and as such: the rear view is a mirror opposite of the front view, and the right-side view is a mirror opposite of the left-side view.