The melee weapon of choice for Monk and Puppetmaster, Hand-to-Hand is a very powerful melee choice, emphasizing pure melee damage potential. Technically-speaking, Hand-to-Hand is a two-handed weapon class, but their damage and delay is calculated in a way unlike any other:
The damage of a hand-to-hand weapon differs from other weapons in that it is added to a character's natural hand-to-hand damage. A character's natural hand-to-hand damage is calculated simply by multiplying his/her Hand-to-Hand skill by 0.11 and then adding 3. When calculating the Weapon Rank, however, the number used as the Weapon Base Damage is the number displayed on the weapon plus 3, with no contribution from H2H skill.
This means, for example, that H2H damage is capped slightly lower than other weapons with equivalent damage rating. For example, Destroyers weapon rating with capped H2H skill is 53, but its damage cap is equivalent to another weapon (sword etc) with a weapon rating of 50 (since its Weapon Rank is computed using 18+3=21 instead of 53).
Note that this can be a problem when using current damage calculators for FFXI, since they assume Weapon Rank uses the same number as weapon rating or equivalent Weapon Base Damage, and would therefore give slightly inaccurate values. To fix this problem with H2H weapons and other weapons which have different weapon ranks than predicted by their weapon rating (maneater, blau dolch, etc), a damage calculator would have to ask for both the weapon rating and Weapon Rank separately instead of trying to calculate one from the other.
A Hand-to-Hand weapon's delay works in the same way as its damage. A character's natural hand-to-hand delay is set at 480, and can be reduced with a Monk's or Puppetmaster's Martial Arts. The multiple Martial Arts traits that a Monk has allow its natural delay to go as low as 300. The delay you see on an hand-to-hand weapon is the amount of delay it is adding to your natural delay.
NOTE: If a character does not have natural Hand-to-hand skill, and does not have a support job with natural Hand-to-hand skill, your attacks will only swing with one fist instead of two, but the delay will still be the same length as if it had two. e.g. A RDM/WHM with a H2H weapon only swings with one fist, but a RDM/WAR or RDM/MNK will swing with two. Further, if you have Hand-to-hand merits, a job will still be unable to swing with both fists or use Hand-to-Hand weaponskills without natural Hand-to-hand skill.
NOTE 2: While equipped with a shield a character will swig with only 1 fist and will technically be using any Hand-to-hand skill it may possess and will not have access to any weaponskill.
NOTE 3: Hand-to-hand weapons do not apply for the typical bonuses granted by the job abilities Hasso or Seigan, nor is the delay of hand-to-hand weapons reduced by Dual Wield. Martial Arts is the only job trait that affects the hand-to-hand class.