Ok, I'm still trying to figure out if I should invest the time in these. Seems like there are conflicting reports and I'm trying to clarify. So, hypothetical situation:
RDM/BLM on Earthsday casting on some typical mob with no special resistance.
Let's say that RDM casts Slow. The spell MIGHT gain a bonus from being an earth based spell on earthsday, but its sort of random. Now if that rdm equipped the earthsday obi, it seems like everyone agrees they would then be assured of gaining the full bonus of earthsday. But lets say that rdm casts something like Drain, using the corresponding obi (this one). Do they gain the full benefit of darksday? I'm really hoping that is how it works. If so I'm going to make it a priority to get the full set. If not... they don't seem to be very useful, situationally great, but it would be hard for me to justify 8 inventory spaces for such a situational piece.
EDIT: Since it's been a while and nobody responded, I doubt anyone checks this page really... but for anyone who has the same question I did... it only enhances the bonus of the current day. So on earthsday you would get a bonus to slow if you had the correct obi, but no bonus to drain with the correct obi... sort of a let-down in my opinion...
Edited, Sep 20th 2007 1:51pm by TheManthraInTheHat