As an aside, the closest thing we have right now to raising our Base Resilience is upgrading The Handle and Stardust Striker so that we get high dice rolls added to our defensive string.
Not a good idea at this precise moment, but worth keeping in mind.
One other thing to consider is that demons greatly respect strength. Its the whole philosophy of the UD.
In that respect, winning quickly, in one or two attacks, might be better simply because it makes us appear much stronger than we actually are.
There's strength in appearing
unstoppable, in winning with but a few strikes.
And there's also strength in appearing
invincible, in taking everything the enemy can dish out and shrugging it off not any worse for the wear.
Frankly, assuming that The Handle does improve MM (which isn't a guarantee, yet, unfortunately), the highest damage output we can give is via The Handle (5) + Aetheric Tide (3). Which gives us 120d375, x2, twice in a turn. That's 600-ish damage per hit, on average.
Despite your claims to the contrary, Aetheric Tide at just LVL 5 presumably deals 200d75, x2, damage, which tops out at 550 (490 after damage reduction) - and isn't really enough to one-shot the demon. Even two-shotting is iffy. Since, again, we don't know which weapon, if any, upgrades MM. For all we know, the formula for Defiance MM is (Sum of All Weapon Levels *15).
This is why my EXP Plan has Defense as primary, damage as secondary, and HP as tetriary just in case. With assumed 475-to-975 damage reduction without MM, we have better than even chances of getting 700+ damage reduction, which cuts the enemy damage to zero, before any spell boosts he might have. In addition, this would probably give us the best leg up for the situation where demons decide that no, they want to wreck our face anyway. After all, it's the strongest soldier under the demon commander. Damage-wise, 120d75, x2, isn't all that much to write home about, but that's still 240-to-390 damage, or likely kill in four attacks. Less than a minute.
Still - an excellent point about Stardust Striker being one of the best possible defense boosters we have outside of
Conundrum. Well, Laser makes even more sense for it now - it's not just a kill-the-heavy weapon with very good damage output (2nd best overall), it's also a survive-a-hit weapon too.