These (Hardy Pants) are Terra's common drop, while it's rare drop is the pair of Enduring Pants. Both look like plain "old world" black leather on Humans, and brown leather on Iksar- safe to assume it looks like plain leather on all races.
At the level one could get experience acquiring these the AC:WT ratio is acceptable, but by mid-higher levels these are about useless to melees, except for perhaps Monks (and Beastlords?) who have fewer alternatives than other melee classes.
Terra, and all the other "big" named Ele's (Hydro, Inferno, and Aero) seem to be on a 4 day timer. In the week-long time that I have spent AE-clearing Ele' Isle, I have had only one named spawn per 24 hour period, with an "uncommon named" (berzerk, hulking, swift, etc) appearing about once every two hours or so.
Re-spawns are pretty fast, somewhere in the range of 10-15 minutes, and some of the elementals were blue and light-blue to a level 40 character. With 2 high-level characters, I was never able to keep to entire Island cleared.
Lower level characters BEWARE- once KoS to Ele's it will be easy for an individual or small group to be overwhelmed with adds during a fight.
This area is lousy for farmers, thankfully, but an excellent alternative to Unrest and Upper Guk for powerlevelling through the 20's and low-mid 30's beacuse of the decent re-pop rate, and decent rare drops.