You quite missed the point. 15 elemental resistance means dick by itself. It will not reduce damage by any observable amount. If you're in a situation where you can predict the element of the spell to be cast (e.g., Jailer of Faith), that 15 Earth Resist might help, but you'd do just as well to be idling in Wind or Auster's Staff since you should own that already. Numinous Shield +1 is not accomplishing anything for you. The only shields worth equipping, really, are Legion Scutum (for -Enmity and +hMP, so a good full-time option with Templar Mace) or Genbu's Shield (when you're likely to be taking physical damage, which isn't often).
Also, idling in -Enmity is moronic. If you're idle, you're not doing anything, so you're not accumulating Enmity.
You quite missed
my point. I cast barspells religiously, even when I can't predict the specific element. I said earlier that 90% of the damage I take on WHM is elemental AOE, well probably 70% of it I have the appropriate barspell up for. Likely more than 70%. If your number is much lower than that, I'd question whether you're even paying attention at all.
Standing in Genbus or Terras is silly, in my opinion, unless you anticipate pulling hate or fighting a mob whose nasty AOE is physical damage rather than magical (admittedly not unheard of and I've done this before but it's extremely rare). Also, I don't own any ele staves aside from Apollo/Pluto/Terra, so I can't always equip the corresponding ele staff for elemental resistance. Remember, thanks to Alkalurops, it's no longer important for WHMs to have every single ele staff. Plus standing in Seveneyes/Num+1 also adds HP in addition to the elemental resistance. For helping survivability, I really think Seveneyes & Num+1 is the best standing pair.