VRAICCI may be a case of confused diphthongs as VROICCI would be expected for OIr. Fróech, fróech 'heather' (McManus 1991, 107, 121).
MEDVVI, OIr. Medb masc. and fem. related to mid 'mead' (McManus 1991, 107, 122). The fact that -I endings are in tact in both personal names would suggest a pre 6th century date.
Macalister (1945, 16-7) prefers not to speculate as to whether this inscription could refer to Medb, mythical Queen of Connacht but it is hardly conicidental that this name is found here. 'The name Fráech is also associated with Cruachain as the hero of the early tale Táin Bó Fraích... Carnfree ('the cairn of Fraech'), a burial cairn some 6km to the south of Rathcroghan, also preserves an association with Fraech.' (Condit and Moore, 2003)