Thank you very much for your input, gentlemen.
Rest assured Geraint, I ignore none of the comments kindly given here.
However, I still wonder about the second kanji on the nakago, for Shinryūshi Harushige is written as 春茂 ?
As for presenting the tantō for shinsa, I'll have to wait till next year's Japan Art Fair to see Hataya Daisuke-san, or sooner if an NBTHK meeting takes place in a neighbouring country. With the Belgian laws on sending "blade weapons" by post or courier, that is the only option left. Anyway, if a shinsa takes place and yields some interesting result, I'll share it here.
Thanks,
Pierre