Why Double Attack?

Why does SE keep adding gear with Double Attack for jobs that can't use it? Well... I think it's time for a little math:

 Blue Mage gets a natural 12% Double Attack before the trait. Let's assume for the moment that they have no other access to Double Attack. A successful Double Attack on a weapon skill, let's say for Vorpal Blade, will effectively increase the Weaponskill damage by 25% (4 hits, +1 Double Attack'd hit). However, if you are Dual Wielding, all your weaponskills actually receive an extra hit, so to be perfectly precise, an extra hit on Vorpal while Dual Wielding should be a 20% damage increase. 


Additionally, you have an increasingly unlikely chance to Double Attack more than one hit of the weapon skill. The chance of two hits would be 12%*12% = 1.4%, three hits would be .17%, and all four hits would be a miniscule .02%, but that wouldn't be possible if you have a Dual-Wielded hit.

Now, if we calculate the expected value, we can see:

12%*20% + 1.4%*40% + .17%*60% = 2.96% increase in WS damage.

(P.s. you can't induce a weaponskill to hit more than 8 times)

On average, you're doing about 3% more WS damage, but you're also producing WS damage spikes ~10% of the time. If we consider WAR sub or the highly unlikely Double Attack trait on main, we're talking about approximately doubling that expected value to about 6% WS damage increase, before Critical Hits and copious ATK bonuses from Food/JA/Spells.

Unfortunately, Double Attack's effect is more pronounced on weaponskills with fewer hits. On Savage Blade, which is two hits, the calculation would be as follows (again assuming you are Dual Wielding):

12%*33% + 1.4%*66% = 4.9% Increase

I'm not sure if the Dual Wielded hit is subject to Double Attack, but adding that in wouldn't significantly increase the WS damage in expectation. If you had the Double Attack trait, that's an approximate 10% increase to Savage Blade and Expiacion.


This is why I overtly hate SAM. A powerful, one-hit Weaponskill that experiences a Double Attack proc is effectively increasing its damage by 100%; an 800 Gekko becomes 1600 when it is Double Attack'd, and SAM has greater access to Double Attack than any other job (except possibly DNC now). Even at 20% DA, which is not at all hard to hit on SAM, that's a 50% Weaponskill damage increase in expectation. On top of that, a one-hit weaponskill caps at 95% chance to land; multi-hit weaponskills decline precipitously in their accuracy per each additional hit. Asuran in particular, which naturally hits the 8-hit cap, only has a 66% chance of all 8 hits landing at capped accuracy.

This only accentuates the need for Square-Enix to figure out what the hell they're doing with lighter DDs. If BLU's balance is found in spell-spamming, you'd better give us a lot more MP efficiency/Endurance (hello, RDM?) and Subtle Blow to be able to at least sort of keep up with the heavier DDs. Alternatively, you could make mixed-damage more useful... Heaven knows there's only like 3 mobs in the game you need both Magical and Physical Damage for, and we don't have enough mixed-damage spells for EG mobs (Piercing-type Cannonball, WRU?), nor do they require it (Plantoid HNM, WRU?).

The important thing to note here is that a successful DA proc will outdo even a large ATK increase on most weaponskills in expectation. Furthermore, DA is more difficult to furnish than ATK, so, I personally prefer it to ATK, which I can get in food and buffs, unless I happen to be at a ATKvsDEF margin.