If you look at the difference in experience needed to increase Essence between what the Solars and the Terrestrials and the difference in the size of their Essence Pools for instance Solars have Essence x 3 in their Personal Essence Pool, Terrestrials have Essence; Solars have Peripheral Essence of Essence x 7, Terrestrials have Essence x 4. That should give you an indication of the difference Essence to Essence between Celestial and Terrestrial Martial Arts Charms. Also Terrestrial Charms would require less Essence because Terrestrials have smaller Essence pools. So for Celestial Exalted they're more like tricks.