Lengthly engravings could be tameshi-mei, or sword-tester's inscriptions, which were generally marked into the tang. After the sword is forged, it would be given to a professional tester, who would make various test cuts. Sometimes these cuts were made on human bodies (criminals or cadavers). The inscriptions detail the cuts that were made, and acted as a form of certification that the sword was of a certain quality. If authentic, and a known tester, it can establish fairly precisely the origins, age, and even provenance of the sword, and greatly increase its value as a collector's piece. If that's what the inscription is, of course.

The scabbard, from what I can see of it, looks like a shirasaya, which is a plain wooden "storage" scabbard used for unmounted blades. That suggests it was not a WW2 weapon (gunto) but rather a personal heirloom that was surrendered after the war when ownership of swords had been prohibited. The blade looks like it has been neglected, but it does appear to be a traditionally forged blade, not a mass-produced gunto.

If the tameshi-mei theory pans out, I'd definitely consider an appraisal.

Japanese history is not my area, but i can tell you how to post pictures. Simply go to http://imgur.com and select new post, from there follow the onscreen instructions to post digital pictures.

You would probably have more success if the real experts can see the pictures.

http://imgur.com/NQ8sxLD http://imgur.com/zHD6BVA Here are the photos. I brightened the photos as best as I could so the engravings are slightly more visible.

Here are more photos of the sword if that helps. The entire blade measures near 3ft at about 35 1/2inches. https://imgur.com/a/ceCVg