Considering it's a level 40 weapon, there's no reason it should be decent at 99. (Even moreso, it should not be able to compete at all with the elemental weapon magian staves, as there are 8+ of them versus the one staff).

Other than that, if SE allowed us to have magian upgradable gear prior to 75, I think this would be totally awesome! If I had been a BLM at level 40 who could spend days getting a trial weapon of MAB+5 MACC+5 to use between levels 40 and 51, I'd totally jump on it!