What would SE have to put on a shield for you to consider using it?

[Greatguardian]

I don't think simply lifting the cap alone would make shield viable. If I recall correctly(seriously, correct me if I'm wrong, I'd like to know), the delay reduction from Dual Wield III is roughly equivalent to an extra 25% haste, plus the bonus from Suppanomimi. So even if wearing a shield removes the cap, you'll have to come up with an additional 30% Haste gear just to break even on delay reduction, and you'll still be missing out on the benefits of the off-hand.

Don't get me wrong, I miss using shields myself but I just don't see it gaining ground beyond incredibly niche setups unless it's complimented with something else.

Unless of course you meant breaking the 80% hard cap, in which case Red Mage would simply become the new zerg machine swinging faster than a Monk with a Kraken Club and Hundred Fists up.

In terms of delay reduction, it's impossible to directly quantify a relation between Dual Wield and Haste because their effects are multiplicative.

If you're assuming 40% Haste (gear+spell), then the comparison looks like:

X = (0.70)(0.6) = 0.42, so it's the equivalent of adding 18% Haste to your previous 40%.

If you're assuming 0% Haste, then DW3 + Suppa is equivalent to 30% Haste.

The best case for Dual Wield from a pure delay standpoint is one where you have no Haste.

However, Dual Wield only increases your TP phase damage while leaving your WS frequency the same. Haste increases both TP phase damage and WS frequency. Therefore, if you had a choice between 30% Dual Wield + 72% Haste and 80% Haste (both of these cap delay reduction), 80% Haste would always be the stronger option.

Dual Wield starts stronger, but ends weaker. If you have access to zerg-tier buffs at all times, then Dual Wielding will actually decrease your overall damage (discounting offhand hits on WS and stats on offhand weaponry, of course).