1hand (dualwield) vs. 2hander

Weapons Mist of Pandaria
Post updated to patch 5.4(click here)

Today’s topic is somewhat of a grey area, at least for me.

WEAPON’s, to dualwield or to 2hander.

Weapon choice has an effect on a couple spells: Fighting Style which morphs Jab into another abilities (only cosmetic or rp-flavored) and Way of the Monk.

The only thing that interests us here is the Way of the monk which when you dual wield will boost in 40% your auto attack, and when you use a 2hander it will increase your melee attack speed in 40%.

They should balance one out so it would be a cosmetic choice, or a choice depending on which one you have that is better.

It's unclear at the moment which weapons will be the best choice for a dps monk, but it's worth noting that, if all other things are equal, dual wielding tends to edge out.

Doing some preliminary math.

At the time of this post, the passive provides 40% increased attack speed with 2h weapons and 40% increased autoattack damage when dual-wielding.

Let’s use the damage stats of
Dragonshrine Scepter and Axe of the Tauren Chieftains.
Both are Strength-based weapons, but stats other than weapon damage are of no interest to us at this point.
Note that both of these had their weapon damage and dps increased in MoP.

It should be noted that Monk abilities that rely on weapon damage all account for off-hand damage as well.
Ability damage will still vary because of AP normalization, but that requires way more calculations, so we are only going to look at  autoattack damage here.

DPS is the median of min and max attack damage divided by attack speed.
Attack speed is calculated as base weapon attack speed divided by all haste and attack speed increases multiplied.

Base auto-attack DPS:

/                   Min               Max              Speed          DPS
2h                4285            6429            3,6               1488,1
1h main       2008            3731            2,6               1103,7
1h off           1004            1865,5         2,6               551,8
DW               3012            5596,5         2,6               1655,5

Auto-attack DPS accounting for Way of the Monk:

/                   Min               Max              Speed          DPS
2h                4285            6429            2,6               2083,3
1h main       2811,2         5223,4         2,6               1545,1
1h off           1405,6         2611,7         2,6               772,6
DW               4216,8         7835,1         2,6               2317,7

That was without any haste or attack speed buffs.
Now, let's assume the Monk has the 10% attack speed raid buff and 25% haste from gear:

/                   Min               Max              Speed          DPS
2h                4285,0         6429,0         1,9               2864,5
1h main       2811,2         5223,4         1,4               2974,3
1h off           1405,6         2611,7         1,4               1487,2
DW               4216,8         7835,1         1,4               4461,5

So as we can see, as always, DW outscales 2h in pure auto-attack damage very fast.

Decimals might be off by 0.1 because Excel rounds differently from Blizzard.

Source: http://elitistjerks.com/f99/t129814-windwalker_dps_flurry_tender_fisting/#Gear, http://mop.wowhead.com/spell=108977/way-of-the-monk#comments