Origin story
Subrahmanya received the vel from his mother Parvati and led the divine army against Surapadma. The demon's defeat is celebrated in the Skanda Purana, and the spear remains the god's defining emblem in the south.
Subrahmanya is the ever-youthful commander and the guardian of spiritual knowledge, especially in Kerala and Tamil Nadu. The vel is spiritual insight, the peacock is the tamed ego, and the serpent is the coiled kundalini energy. His shrines at Peralassery and elsewhere keep the festival of Thaipusam and the Kavadi tradition alive.
Source: Wikipedia: Kartikeya — https://en.wikipedia.org/wiki/Kartikeya
