Richards said:
As far as the concealment ability of a dagger goes, I remember hearing about an AD&D 1st Edition wizard PC who had so many throwing daggers concealed on various parts of his body (strapped to all four limbs, secret sheath on a belt, hidden inside belt pouches, equivalent of a "shoulder holster," etc.) that his DM granted him an AC bonus on the theory that many weapon strikes were bound to hit a concealed dagger rather than the wizard's flesh!
Johnathan
Huh, I allowed that IMC, many moons ago; a female magic-user (ouch, that dates me) would loot as many knives and daggers from the slain foes of the party as she could, and had them strapped all over her. In combat she would stand a bit back and throw knives and daggers (her decent DEX helped quite a bit) when she ran out of spells. She usually made the party ranger look silly cos she would hit more regularly, do more damage and slay more enemies (low-level party, usually facing orcs, goblins, kobolds, hobgoblins, gnolls and ogres) than he did.
It was sad and funny at the same time.
So, anyway, she had so much steel strapped to her (and she was a real petite flower, 5' tall) that I let her have an AC bonus.
Crazy character, though; she went insane and fell in love with a kobold.
On the value of the dagger: looks like all the good points (

) have been made. Useful as a tool, as a backup ("last resort") or main weapon, makes a good eating utensil, is unlikely to raise suspicions, is lethal, does piercing/slashing damage, can be used to bonk people on the head or slug them in the gut (with the pommel), is easily concealed, can be used as a melee or missile (thrown) weapon, is finesse-able and is a common historical, fictional and present-day weapon that can look
very cool.
Every character whom I've run in 21+ years who could, always had a dagger, and many times that weapon spelled the difference between life and death.