What is Double Hand (DH) and why should I care? What is True Double Hand (TDH)?

Double Hand (DH) is a passive attack boost that uses your equipment's flat attack value. For weapons, this is easy, its the attack value of the weapon. However, other items can also have attack values and this is boosted. DH only works for one-handed weapons.

The cap for DH is 300%. So a 100 attack weapon gives you the base 100 attack plus up to 300 extra attack from DH passive.

True Double Hand (TDH) is the same as DH, but works with two-handed and one-handed weapons. This is important because two-handed weapons typically have a damage multiplier called weapon variance. Typical two-handed average weapon variance is 1.3 or 1.5 and Fixed Dice has 3.85.

There are various ways to gain DH:

• Innate (Cloud 100% TDH, eOlive 150% DH, ExAileen 100% TDH, eRandi 100% DH, eDRain 150% DH, Moogle 50%, Ang 100% TDH, Aranea 100% TDH, Cor 80% DH)
• Materia (Cloud TM 100% TDH, ExAileen TM 50% TDH, Bartz TM 50% DH, Double Hand materia from King Mog 50% DH)
• Weapon (Olive TM 50% DH)
• Accessory (Elfreeda TM 50% TDH)

Chart

See this chart. I've terminated the lines at atk values that are currently achievable in global.

This chart contains the bolded parts below:

(Atk² / def) * Element * Killer * Skill Mod * Chain mod * Weapon Variance (* Level * Variance)

This chart can be used to quickly compare the difference between dual wield (DW), doublehand (DH), true doublehand (TDH) and TDH Fixed Dice (TDH FD).

How do I use it

Lets take eAileen as an example, she has a 75% imperil. Her BiS for DW-TDH-TDH:FD are (1163-1634-998). From the chart she deals 3.6m-4.75m-6.82m (3.9 from normal FD * 1.75). So it is clear to see that her FD build, even with a turn imbuing, would be destructive. Of course, not everyone has BiS.

But most of us don't have BiS TDH. At least, not if you will find this graph useful.

Remove buster style to get new atk stat (1163-1380-899) = 3.6m-3.4m-5.6m (5.6 = 3.2 from normal FD * 1.75). DW is better than TDH, but worse than TDH:FD. The actual damage of TDH:FD is 4.48 (=5.6*(4/5)) as you lose a turn imbuing. The chaining modifier will be worse and it might not fit with the enemy rotation/thresholds.

One marshal, one tomb raider (1163-1322-852) = 3.6m-3.0m-4.9m (2.8 from normal FD * 1.75). The actual damage of TDH:FD is 3.92 (=4.9*(4/5)) which would not be a great enough benefit to be worth having to rotate in imbue and your first-turn damage is much less - 2.8m compared to 3.6m.

Explanation

The main differences are:

DW - Hits twice so is great for chaining and other effects proc twice (ExAileen LB fill, Noctice LB fill). Imperils are included for DW using the 1.0x1.5 (where the 1.0 is the weapon variance and 1.5 is the element imperil). The imperils provided are 50% (1.5), 75% (1.75) and 100% (2.0). Typical units for each would be: 50% - Orlandeau, Dark Veritas. 75% - Ace, eAileen. 100% - Tidus max LB. There are many more external imperils, but you need to find which one is useful for you.

DH - Increases atk by a percentage of equipment flat damage when equipped with a single one-handed weapon. The benefit over DW is increased atk for finishers. The benefit over TDH is the availability of elemental weapons. The weakness against DW is only hitting once (unless using dual-cast 'W' skills).

TDH - Increases atk by a percentage of equipment flat damage when equipped with a single two-handed weapon. The benefit over DH is weapon variance. Otherwise, the same comparison as DH.

TDH:FD - This is a subset of the TDH build where the unit equips Setzer's Fixed Dice. The weapon variance ranges from 1.2-6.5. The average is x3.85, which is more than double typical two-handed weapons (and 3.85 one-handed weapons!). However, it only has 1 atk stat so greatly depends on BiS TDH equipment to achieve high attack value.

What this chart does not include

Effect of chaining modifier on damage output. See DefiantHermit's post.

Effect of imbuing TDH and the reduced damage per turn. I have started looking at this because Verun provides a reliable source of imbuing Fire|Wind|Earth, but that will be a future post.

Effect of an LB heavy chainer - where the unit damage is increased significantly by LB - as DW would be much less effective (e.g. Tidus who needs LB to imperil and can only spark chain when DW or reduces damage 50%).

Other

What I have found interesting is that Dark Veritas' 100% counter imperil makes him a as good DD as Orlandeau if it is up half the time (20% chance for 3 turns means that being hit two times with physical should be enough for 100% up time after turn 1) - so bring out Glauca's Greatsword!

Notes

All lines account for 100% atk buff on a base of 185. DW accounts for dual 135 atk weapons which I think is a good balance for weapons like Aigaion arm, Excalibur 2, Onion Sword etc. Lower atk weapons raise the DW lines slightly (but, of course, it is harder to reach the higher attack stat).