Well I'll take this chance to trow in my own vieuw of unarmed combat.
It's benefit to using a weapon is the pysical contact, you make a closer contact to the target, this adds interesting capabiletys.
Fealling for instance; you can touch and feel your target if you have your hands free, this allows for pressure point based skills, that parelise your foe or specific lims for a while.
Grabbing; not holding anything allows you to hold your opponent, this opens up skill lines that floor, toss or pinn your opponent.
Energy transferance, sertain magic will be stronger when physical contact is presant, though GW probably covers this just fine with touch attacks, still some preperations that affect unarmed weapons might have a use.
As for unarmed weapons(yes weapons, I know it is language wise wrong but I'm calling them that, sue me)
A unarmed weapon has to be equipable, without inscriptions and upgrades and bonuses it would just be unfair and unbalanced and not verry GW like(a class that does not have any greens imagine that)
They should be katras, a katra is sort of like a combat style, its a martial arts thing and is a beginning positions and all the assotiated actions.
For with most martial arts youre suposed to move way to fast to see and anticipate what your opponent is doing, else they could see what your next action would be which would be bad.
There for they practice catras, sort of like a dance really 1...block...2...punch...kick...3 they are there in short and long, simple and complicated, deadly or subduing varietys.
I think every form of martial arts has more than one katra, kunfu has at least 23 likely more, as people often say to have their own style of it.
These katras would be equipable as 2 hand items, and have pretty small damage but really fast reswing times 0.60-0.80 like I guess, and effects on the X'th attack and X% to cause <effect> on the X'th attack. the last attack slowing your attacks for a while, mimicking the time needed to ready yourself for a combo again.
That said I think assasins do have some sort of hand to hand covered, though its not really anything more than a few touch attacks, instead of fully creating a new class I see hand to hand being implemented as a abilety to first monks and maybe assassins.
Monks because it fits their theme(seen them dance have you?) assassins becasue they already have some and would ofcouce not be able to be left behind if it where extended.
monks could like have a katra that blocks melee attacks on the first and third strike, instead of dealing damge assotiated with protection prayers.
For smiting prayers they could have katra that is more aggresive and may knockdown foes.
Disclaimer

Note that I said sort of like styles or dances, it is in truth much more complicated with 1 katra having 5 diferent befinnings transferring into the same folowup, and anticipations for which way to go through a catra depending on the opponent and situation, making anticipation nessesairy.
I was just giving a very rough idea of what it is about, an expert will agree I am definatly nor qualefied to explain something like martial arts.