Nukes!!!

[Selindrile]

Dual wield wouldnt really fit a WHM main since its trait mainly for ninja and thf/dnc really.

At this moment in time, sure, but historically this was not the case, the most common dual wielder in the first years of the game was War, and soloist-Rdm (both subbing Nin), Nin did but it wasn't used as frequently, though after some time, Nin did become more widely used and was the Pre-eminent dual wielder.

Thf only got dual wield natively somewhat recently, though they often subbed Nin for it, often they didn't. You also forgot to mention Blu, they were in a similar boat to Thf for a long time, frequently subbing Nin, but not always. Also Whm/Nin was not too uncommon, old bones parties and Whms soloing things pretty frequently comes to mind, but they didn't do it as often as Rdm did.

Traits are only "mainly for ____" until they're not.

Banish tho is something that WHM should have up to max tier as its the only real offensive spell whm has. As said before the last spell in that line WHM gets is at lvl65 yet mobs and npcs not only have the -aga 3 version but high tier use banish 4. Why WHM never got these like blm got tier 5 nukes is a mystery so far.

While I don't necessarily think Whm would get less out of higher tier banishes than offhand clubs for more Macc, I see no reason not to give them both, it wouldn't break anything, and it would be fun, to use your words, neither of these things would harm anything, or even rebalance anything. (Again, you could put an attack speed penalty in for DW0, high as you like, to discourage people from meleeing with it without /Nin, if you like.)

Its no harm for Whm to have max level spells anyhow and its one of those missing leftovers from the level cap raise.

Also Blm should have tier iv aga elemental spells as well.

While at heart I really have no problem with this, considering Blm's position in the game at the moment, maybe wait for another time? But, honestly, it would probably be fine.