From The New York Times, 1904:

The Hatpin Inflicts a Severe Wound and Can Be Got Ready for Action in a Moment

“What shall we do in case we are attacked by some thief or ruffian?” is the question women have asked in every part of the country. The man to whom the question is put will generally answer: “Carry a revolver.” But women dread revolvers. Few women possess the nerve necessary to use a pistol with effect when attacked. Then there is the objection to a revolver in the possession of a woman that she would be averse to suspecting the motive of every man she met and would probably fail to draw the revolver until too late, for fear of making a foolish mistake. What, then, can be provided for her that will be formidable to a foe, yet absolutely safe, so far as she is concerned, and ever ready at hand, whether wanted for use or not?

The answer to the puzzle has been provided by those who make women’s hatpins. A hatpin has been designed that is intended primarily for use as a weapon of defense. It is in reality a stiletto, masquerading as an innocent hatpin. It is made of fine steel, that will bend, but will not break, as sharp as a needle, and hardened at the end so that it can be used with deadly effect as a dagger, and a handle that enables a woman to grasp it for use as a weapon and hold it so that it cannot easily be pulled from her hand.

There are two ways of holding this hatpin. It can be held with the thumb pressed against the top or with the button grasped in the palm of the hand. In either way it is a weapon not to be despised. The method of using it to the best advantage when attacked is to aim at the face of the highwayman. A woman armed with one of these stilettos is able to do more damage in a few seconds than a man unarmed. The wicked little blade is so small that it is impossible to grasp it to wrench it away from her, and yet so keen is it that, thrust home by a woman frenzied by fear, it is likely to pierce through any ordinary clothing into a vital part of a highwayman’s anatomy.

There are times in most women’s lives when a suspicious looking character comes into the offing and prudence whispers: “Beware of him.” While most women would shrink under these circumstances from pulling out a revolver, it is an innocent act to put the hand to the hat and draw out one of her stiletto-like hatpins. With this in her hand the nervous woman is ready for the stranger, whatever his Intentions. If he is an honest man he will probably take no notice of the woman’s action. If he is a thief, it is more than probable that he will mark the act and let the woman pass unmolested.