If I am right that INTI is an abbreviation, which are frequent on inscribed objects from antiquity to modern times, it may well stand for 'intimi', 'inmost, nearest', and so 'dearest, most high, most serene' Cf. Lewis & Short s.v. 'intimus'. DOMNNI is almost certainly a misspelling for DOMINI. To judge from the description of the sword, used by a mercenary bodyguard of the Venetian Doge, on the webpage referenced by the asker as being of Eastern European, apparently Byzantine, origin this inscription seems to mean, more colloquially put, '(My) Serenere Lord's (Property, Gift, etc.)'.