From Markus Sesko's Index of Japanese Swordsmiths:
Sukemori (助盛) Tenbun (天文, 1532-1555), Bungo - "Taira Sukemori Saku" (平助盛作) Taira-Takada school, suguha, gunome midare.
The shape of the tanto is attractive, and not so common in koto blades. Worthy of taking to Shinsa, I think. Your blade would also benefit from a re-polish; as you said, the current polish obscures the hada. Usually polishing is not advisable in financial terms, but tanto polish is not too expensive compared to the blade value. Better to take to Shinsa first, however, since polishing a Gimei blade is a waste of money.
Veli