Skills for Rune*, regular attacks for everyone else**. The "deathable" skills I use the heck out of since they almost always work in random battles whereas the "deathable" techniques I avoid altogether for the following reasons--
--[Sa]vol is unique to Hahn and works only on biomonsters. That in itself is not so bad, but it cuts into his TP pool which IMHO is more valuable for Wat and Res.
--Brose supposedly works on all enemy types, but supposedly has a higher success rate vs. machines. Even with that factored in, the success rate is still too low. Gryz would have been better off having no techniques or Shift as his sole technique (but he already has War Cry).
*Assuming the Dual Shield set up, otherwise, he has no offensive output during dungeon crawls.
** There are some skills, like Airslash and Disrupt, that are useless in boss battles but incredibly handy during multi-enemy encounters. I consider them "regular."