Exceptional Agility

The glow effect is the same as on the standard Agility enchantment, i.e. green.

I'm no theorycrafter, but 18 does not = 1/3 of 60. neither does 15 = 1/3 of 60 which is the more accurate figure to use in calculating mongoose given that mongoose is normalized to 1PPM and allows for natural variation (ie. the chance that mongoose does not proc at all). the final equation should be 120/4 = 30. So mongoose equates to ~30AGI.

The Mongoose buff lasts for 15 seconds. It is up 1.2 times a minute. This is 18 seconds out of every minute. (15 * 1.2 = 18). This means the buff is up 18 seconds out of the minute. This is 1/3 a minute. (18/60 = .333 = 1/3). The buff of 120 agility averages out to a constant 40. (120/3 = 40). 15 * 1.2 = 18seconds/min. 18/60 = 1/3min. 120/3 = 40constant agility. Mongoose translates to 40agility per-second. (Edited to reflect the deleted comment)