Brand of Earth is a Carpenter ability learned at rank 20. If you want it, I'd suggest levelling that craft. According to the Wiki article, your next ability is Pre-emptive measures at level 30, which reduces the chance of element destabilisation.
Abilities, even 'passive' abilities (called Traits), need to be equipped before they are active. You can equip any ability from any Disciple of the Hand class, so level a range of crafts for the best chance at success!
Edit: Amended rank needed to learn Brand of Earth.
Edited, Nov 9th 2010 12:00pm by Glitterhands
FFXI: Siren Server: Seiowan Lvl 99 WHM, SCH, BLM
FFXIV: Ragnarok Server: Lemuria Glitterhands All Classes 50