I changed the diff on top-tier phials. My own testing puts it conclusively at 455 for peas. The figure for individuals was derived from the pattern by subtracting 30 for 425; I have not personally confirmed it.
It looks like someone assumed a pattern that does not persist through mana phials. In the lore itself, it explicitly states that unlike other phials, mana phials are more difficult to make than to wield. This has come up in several conversations on the official forums where some poor soul took Wiki's assumed numbers as true, and was surprised by failures or by others describing an inability to hit 100% even with outstanding gear and toys.
--Elije 06:04, January 22, 2010 (UTC)
I also added a column for wield requirements of the finished phials, as this was buried in the descriptions of the individual finished phials.
--Elije 06:15, January 22, 2010 (UTC)