Shugyosha

The mei bun - jidai column gives it to den Jumyo from around Kanbun.

Looks like you’re going to need more tsuba…

Hi Paul, It’s a date, Teikyou, gan’en saku kore: …made this in the first year of Teikyou - 1684. Sorry, my phone screen is playing up so I can’t assemble the kanji.

Hi Geraint, Sorry, now corrected - thank you!

The usual indicator of age is the length of the kerakubi (the part between the blade and the tang). I would say this is a long kerakubi (the blade in the OP's and Jean's example look short) and this points to it being being Muromachi or perhaps on the cusp so I don't think the description is that far out. Shorter kerakubi normally indicates an Edo period blade.

Hi Andy, This is probably not too much to worry about - it’s an antique blade and if it isn’t going to be used for cutting, it’s just part of the appeal of an older blade.

Hachimonji Chogi; Heshikiri Hasebi.

Hi Harvey, I think you’re safe with Nobody San’s reading. Enjoy your blade!

Hi Uwe, I think I like yours better than mine - other examples of Kanetada I’ve found look different, though they might not be done by the smith. @Roam any chance you could post a clearer picture?

Hi Harvey, Welcome to NMB. I’m not seeing the photos very clearly on my phone but I think 石原兼忠 - Ishihara Kanetada.

I'm trying to see why someone would go to the effort of forging the signature of what could be any one of around 50 low grade smiths rather than one of the better Sukesada?

Hi Milo, Welcome to the forum. 和泉守藤原国貞作 - Izumi (no) kami Fujiwara Kunisada. It's a big name and often faked. You might get some better information if you are able to post some pictures of the blade as people will be able to see the signature in the context of the workmanship. Some more information here: https://www.nihontocraft.com/Izumi_no_Kami_Kunisada_mei.html

Hi Sally, In the separate cartouche at the top is the kanji 長 "naga" or "Chou" meaning long or superior. Below is a place name 小串町 "Kogushi machi" or "Kogushi Chou" - meaning Kogushi town which is a district of Shimonoseki city in Yamaguchi prefecture.

Hi Grev, Following a quick google, this tsuba appeared with what I think is a matching signature (the kanji top left on yours is a little obscured so not 100% sure): https://art.thewalters.org/object/51.267/

Hi Juan, Welcome to the forum. Another thought is that a spear (or indeed any blade) doesn't have to penetrate deeply to cause significant damage and on the battlefield it may be a disadvantage for the user if it does so as it may be difficult to withdraw quickly when needed to deal with another opponent.