Hah, this one is easy for me: Pet: DT-5% on Ohrmazd (Alluvion H2H) for my PUP tanking weapon.
I have an already quite good DT-4% from leaf, and I'm pretty happy with my dusk (STR/DEX/VIT+15) and snow (Meva+20something) augs... but not having the "perfect" DT-5% is gonna irk me until I get it, if 5% is not a myth (I think it's a myth sometimes!)
Occasionally I'll have some extra gil, spare stones, or the prices drop from login campaigns or whatever... and that damn thing always draws me back for a few more failed attempts.
I think it only goes up to DT-4. While the BG wiki page states -5, going to the source on ffxiah has the table at -4. I only ever got -3, so I just went with the reisenjima h2hs.
As for elusive augments, I'm just a bandwagon BLU, so naturally, I got this augment while shooting for 6 fc with fern (35 is non-DM cap for herc, right?). It lets me one shot reisenjima mobs without any amalric +1, so at least it's being put to use.