Similar hilts and guards are occasionally seen on Philippine swords circa the "insurrection period", and of course, on The Ceylonese kastane, with correlations often attributed to Dutch influence from the maritime shortwords or cutlasses, possible in the former two and doubtful but still possible in the latter, IMO.My guess is that the screw is indeed welded to a rat-tail tang for solidarity.
Two incredibly sweet swords by the way...donations to my collection are always welcome, with my address readily available.
Mike