All the same to me Ian! Could be a bird - there is what might be the representation of an eye - even a few indentations that might be an allusion to feathers there on the 'shoulder'. The 'head' resembles a Pterodactyl more than any bird I can think of though - hang on, Crested Ibis maybe?

Can't really see a wing there though; bird and shell maybe?

Cinders, the only thing that catches my untrained eye is the last Kanji has been over-struck on another and the tang doesn't show much age. The extra peg holes if I remember what I read many years ago, were sometimes added to give the impression of age, and it's hard to see how the tang could ever have been long enough for those two holes near the end to actually function. They are far enough out of the way however, to perhaps give 'the look' without weakening the tang?

Any capture history on the sword? Once or twice they've shown up around here with inscriptions in Japaneseicon on old cloth tags attached to the scabbard.