I wonder if they are in some way a depiction of the Kusanagi no Tsurugi and Yata no Kagami, the originals of which are supposedly owned by the imperial family
A sword more than maybe ~15cm longer than its user is tall and heavier than ~6 pounds at most is not usable in combat and was most likely made to show off the blacksmith's skill and by extension his patron's prestige.
Redditor_From_Italy t1_j5y989z wrote
Reply to Longest ‘dako’ iron sword at 2.6m, along with a unique shield-shaped mirror, found in 4th-century Japanese burial mound — Finds indicate that the technology of the Kofun period (300-710 AD) was more advanced than previously thought by marketrent
I wonder if they are in some way a depiction of the Kusanagi no Tsurugi and Yata no Kagami, the originals of which are supposedly owned by the imperial family