If you followed the weaponless conduct, then you never hit with a wielded weapon. Anything in the "weapon" section of your inventory or represented by an ) is a weapon. Three tools, the grappling hook, pick-axe and the unicorn horn, count as weapons. Conversely, applying a bullwhip breaks conduct only if the target is not wielding a weapon.
The best way to follow this conduct is to never wield any weapon, with careful exceptions when not fighting monsters. You might wield a blade to #force open a chest, but remember to unwield it so that you do not hit any monsters with it. If you do wield a pick-axe, be careful to dig without hitting any monsters and to unwield the pick-axe when digging is complete. The rec.games.roguelike.nethack archives do contain stories of weaponless games ruined when the hero whacked some monster with the pick-axe.
Though you never hit with a wielded weapon, you may still fight bare-handed, throw weapons, throw rocks, and use other offensive techniques such as wands and spells. The best weapons to throw are daggers. You also want darts, because you can get them from dart traps and you might need them should you throw all of your daggers. Avoid the bow, crossbow and sling, because if you wield them then you will soon hit a monster with them.
Dexterity is normally trained up in melee; some players kick down doors (with its own drawbacks) or repeatedly pick locks to compensate for that.
What role for your weaponless character? Monk is the most popular and obvious choice. Monks fight best with martial arts or artifact weapons, and you can avoid the latter, preferring spells or wands. The Barbarian is more difficult. Barbarians can still use bare-handed combat, but not the martial arts of Monks, and their difficulty with spells makes it hard to find alternatives to Cleaver and artifact weapons when they must do more damage. Also consider the weaponless Wizard. Wizards can start by throwing daggers instead of wielding them. With one exception, Wizards fight better using spells than weapons. The one difficulty is that a weaponless Wizard must not wield Magicbane, lest he thrust it into a monster by accident. Instead of taking curses with Magicbane, weaponless Wizards should find a spellbook of remove curse and keep a stack of holy water.
6.5% of all winning accounts on NAO have a weaponless ascension.