Nobody

The tag looks questionable to me. The town’s name Miyajima-cho (宮島町) was used after 1950. If the tag was written just after the end of WWII (1945), the town’s name should be Itsukushima-cho (厳島町). At the time, Hiroshima-ken was most likely written as 廣島縣. There are three 島 kanji on the tag. They are all wrong characters. 宮 looks strange. It looks like 官

関住兼松一則作 – Seki ju Kanematsu Kazunori saku (Kazunori’s family name is Kanematsu.)

入隊時の中隊長殿（十九年四月一日） - The company commander when he enlisted (1944, 4th month, 1st day). 陸軍中尉　堀米昇殿 – Army lieutenant, Mr. Horigome Noboru

藤次郎作 – Tojiro made 白紙 – Shirogami Tojiro is a trademark of the following kitchen knife manufacturer. TOJIRO Japan I More than just sharpness Shirogami is a brand name of carbon steel made by Proterial, Ltd.

於津國生玉剣竜子貞晴造之 – At Tsu no kuni (= Settsu province) Ikutama, Kenryushi Sadaharu made this. 慶應四歳辰八月日 – Keio 4th year Tatsu (1868), 8th month

The chiseled characters on the tang are imperfect because of wear and tear. But I think that the second kanji looks like 継 (tsugu). The name may be 義継 – Yoshitsugu. FYI: yoshtsug.jpg (91×250)

It must be a typo. 純正眞鐵入鍛 I do not know its correct reading either. Junsei magane nyutan (?) - Forged from genuin iron.

Just a guess, 蓋好資料之一也 (Kedashi ko-shiryo no hitotsu nari) – Probably, it is one of good examples. 金象嵌 銘曰 ＊ kin-zogan mei iwaku

小林 - Kobayashi (family name)

I think that your reading is correct. The nuance of "... saku ka" is conjecture rather than doubt.

大谷家之紋透鐔 (Ohtani-ke no mon sukashi tsuba) – Sukashi tsuba of Ohtani family’s mon IMO, the hanging wisteria crest on the tsuba looks a little different from the Ohtani’s Sgari Fuji.

東神正国作 – Toshin Masakuni saku 昭和十九年三月日 – Showa 19th year (1944), 3rd month

蓋同銘中無出其右者 (Kedashi domeichu sono migini derumono nashi.) – Perhaps, among the works with the same mei, it is second to none. As for “盡忠則命” on the box, I think that we do not have to be too bound by the word on the box. I guess that the order of the kanji was Kanzan’s own understanding only because he did not know the original four-character idiom 忠則盡命. The attached article was written on the premise that the word was 忠則盡命. Ref. 忠則藎命図鐔　銘　三信家

萬延元庚申年日 – Man’en 1st Kanoe-Saru year (1860) 鈴木鉄造典直迮之 – Suzuki Tetsuzo Norichika/Norinao made this.

下原住正長 - Shitahara ju Masanaga