A Pink demon slayer sword symbolizes love and is appropriately utilized by the Love Hashira, Mitsuri Kanroji. Due to the way her body worked, the composed the Nichirin blade and therefore she uses love breathing techniques to fight against demons. While she might be weak physically, she is still strong enough to take down strong demons.

The Green demon slayer sword symbolizes the awakening of Wind Breathing ability, this particular color of the Nichirin blade is wielded by Sanemi Shinazugawa, who himself seems ironically as unstable as the wind itself.

The red color of a demon slayer sword represents flame and fire breathing techniques. The Red Nichirin blade is wielded by Kyujiro Rengoku, who can utilize it for essentially burning down demons and even using it to fight against upper moons such as Akaza, an Upper Moon 3.

The Indigo-Gray demon slayer sword symbolizes the aspect of “beast” and therefore is highly appropriate as it is wielded by Inosuke Hasibira, who just happens to wear a boar mask and is more or less savage when fighting against demons as he uses multiple Nichirin swords of the same color with sharp and prickly edges.

The Amber-colored demon slayer sword is symbolic of sound and is therefore wielded by Tengen Uzui, the Sound Hashira. The users of sound breathing techniques can utilize their abilities to confuse by noise along with allowing fast movements equivalent to sound itself.

The white-colored demon slayer sword symbolizes mist and is wielded by Muichiro Tokito, the Mist Hashira. Mist breathing techniques follow a more subtle way of combat and the movements are swift along with the techniques being utilized to confuse the enemies by clouding their vision.

The users of Mist breathing techniques also have a calm disposition and are generally quiet in their manners.

The yellow demon sword represents thunder and is symbolical in its usage by Zenitsu Agatsuma, who uses the Thunder breathing technique’s first form. The first firm of the Thunder breathing technique is more than enough to annihilate strong demons and do so in quick succession.

The light pink demon slayer sword represents a flower and is used by both Kanao Tsuyuri and Kanae Kocho, who both acquired the title of Flower Hashira during their times, for their flower breathing techniques.

Flower breathing techniques allow a user to fight gracefully and even enhance their eyesight, however, it does come with the possible side effect of vision loss.

The blue demon slayer sword represents water and is used by Giyu Tomioka, the Water Hashira, for his water breathing techniques. As water is symbolical of calmness, Giyu uses his water breathing techniques to fight in a swift but precise manner to annihilate demons instantly.

The gray demon slayer sword represents stone and is used by Gyomei Himejima, the Stone Hashira of the Demon Slayer Corps and the strongest Hashira of the group itself.  However, he does not use a typical demon slayer sword in this instant, rather he uses a flail-like ax to destroy demons badly.

Stone in itself symbolizes coldness and stoicism, which are ironically the opposite traits of Gyomei, who more or less is the most emotional of the Hashira, even shedding a few tears for his fellow Hashira.

The black demon slayer swords are looked upon with hate and fear as they seem to represent the early death of their user. However, it is later shown that the black demon slayer sword represents the sun breathing technique in its original form as black often absorbs the sun and is, therefore, the most potent of colors.

This specific sword is currently wielded by Tanjiro Kamado, the protagonist of Demon Slayer and who utilizes the sun breathing techniques, albeit in a weaker form.