Acceding to the repeated prayers of the devas and asked Skanda to proceed for war with the daityas by.
- Siva handed Ekadasa Rudras as eleven weapons in his eleven hands.
- Parvati gave in his twelfth hand the powerful ‘Shakti' weapon (known as ‘Vel' in Tamil)
Other than the vel of Adiparashakti Maa Durga, Bhagwan Kartikeya possesses the following divine weapons :
Mahadev’s Trident, Pinaka bow and topmost version of Pashupatastra, Mahadev's divine axe and the greatest lore given by Mahadeva himself
Then Śiva, the lord of the universe, following the worldly convention delightedly placed Kārttikeya on a beautiful gemset throne. Śiva gave him the trident, the bow Pinaka, the axe, the arrow Paśupata, the weapon of destruction and the greatest lore.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 5
Sudarshan chakra and a divine armour gifted by Parameshwara Narayana
Then Śiva, the lord of the universe, following the worldly convention delightedly placed Kārttikeya on a beautiful gemset throne. Viṣṇu gave him a crown, a coronet and bracelets moulded and set in gems, his own necklace Vaijayanti and the discus.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 5
Brahmashirastra
At this time, then guha (kArtikeya), the lord born from fire, angry and blazing with splendor, bit his lips in the battle field and took up an arrow named brahmashira, difficult to defeat like the god of death. As guha (kArtikeya) shot the arrow brahmashira, equal in splendor with a thousand suns, terrible, most difficult to overcome, capable of causing the decline of the world.
~Mahabharata Harivamsha Parva 2.126.8
Another immensely strong and terrific bow of Mahadeva (it's name is not mentioned)
And from the fact of its being regarded by the Rishis as cast off, the child born therefoem came to be called by the name of Skanda. And the limbs of Guha were developed on the fourth day. And being surrounded by masses of red clouds flashing forth lightning, it shone like the Sun rising in the midst of a mass of red clouds. And seizing the terrific and immense bow of which was used by the destroyer of the Asura Tripura for the destruction of the enemies of the gods, that mighty being uttered such a terrible roar that the three worlds with their mobile and immobile divisions became struck with awe.
~Mahabharata: Vana Parva: Markandeya-Samasya Parva: Section CCXXIV
Other divine weapons of Bhagwan Shri Vishnu and Indradeva.
Then all the Devas respectfully gave him the name Skanda because the seminal fluid was spilled on the ground. Divine weapons were given by Mahendra and the noble-souled Viṣṇu.
~Skanda Mahapurana, Nagara-Khanda, Tirtha Mahatmaya chapter 71
Brahmastra, lore, Kamandalu of Bhagwan Brahmaji.
Brahmā said :— I gave him the holy thread, the Vedas, the mantra Gāyatrī, the vessel Kamaṇḍalu, the arrow Brahmāstra and the lore that destroys the enemy.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 5
Divine Shakti weapon of Lord Agnideva
Thereupon, Vahni came there and saw his son Guha who had six heads, ears twice as many and twelve eyes, arms and feet.He saw Fire-god. Thereupon, O son of Pṛthā, Pāvaka (Fire-god) embraced him and kissed him. He addressed him as “O son” and granted him the Śakti missile himself.
~Skanda Mahapurana, Maheshvara Khanda, Kaumarika Khanda chapter 29
Vajra of Indradeva
Then Śiva, the lord of the universe, following the worldly convention delightedly placed Kārttikeya on a beautiful gemset throne. Then Indra gave him a lordly elephant and a thunderbolt.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 5
Adiparashakti Maa Parvati gifted him a divine chariot constructed by Lord Vishwakarmaji. It had speed of mind.
In the meantime he saw an excellent, lustrous and wonderful chariot, made by Visvakarman. It was a commodious with a hundred wheels. It was beautiful and had the quickness of the mind. It had been sent by Parvati and was surrounded by the excellent attendants of Śiva .With an aching heart, Kārttikeya, born of the semen of lord Śiva, the perfectly wise and endless Being, got into it.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 4
Divine chariot and armour of Lord Sooryanarayana, Lord Yama's personal staff/ Kaladanda and weapons of goddess Nirrti and Moongod.
Then Śiva, the lord of the universe, following the worldly convention delightedly placed Kārttikeya on a beautiful gemset throne. The sun gave him a chariot as fast as the mind and a coat of mail with great equipments; Yama his own staff: the moon a vessel full of nectar. Agni lovingly gave him a spear; Nirṛti his own weapon.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 5
Divine mace of Lord Kubera, spear of Mahadeva, Kamdev's mace and his other divine weapons of all the gods.
Kubera gave him a mace; Śiva a spear; the gods different kinds of weapons and implements. The delighted lord of Kāṃa gave him the weapon of love, a club and his own lore with great pleasure.
~Shiv Mahapurana, Rudra Samhita Kumara Khanda chapter 5
Shaila weapon, Varunastra, Saurastra/Savitri weapon.
The one who is born from fire (guha, kArtikeya), becoming angry, by shooting three arrows, shaila, vAruNa (belonging to the deity of ocean) and sAvitra (belonging to the deity of sun), blocked the three arrows.
~Mahabharata Harivamsha Parva 2.126.5
Other unnamed divine weapons and cloud missile.
Remembering the feat of lord Śiva accompanied by Parvati, and taking up weapons and missiles, the sixfaced deity fought terrifically.With his divine missiles, the son of Śiva split the serpents, mountains, trees and rocks, everything furiously. He prevented a conflagration by the missile of cloud.
Divine lance of Supreme Lord Shiva
Then the great angry demon holding a fierce and terrible lance resembling death at the end of the world, hurled it (at Kārtikeya). The son of Pārvatī too burnt it in a moment in the battle by discharging a lance presided over by Pasupati
Mahadeva had also gifted 11 weapons to Lord Kartikeya which were made up of the 11 Rudras/Ekadashrudras. Those weapons were tomara (javelin), sword, shield, bow, vajra, arrow, angusa (elephant goad), staff, mazhuni (axe), ghatmani, flag.
Lord addressed his son immediately. "My dear son Saravana! Devas are being tortured by Soorpdhaman and his asuras for a long time now and it is high time you annihilate them to restore Indra 's kingdom to him." Muruga took his father's command and started on the job. Lord made Ekadasarudras as his son's weapons. They were Tomaram, flag, sword, Kalisam or Vajrayudham, arrow, Angusam, ghatmani, staff, Bow and Mazhuni. They adored Muruga. While lakhs of soldiers came as his escorts, a divine chariot appeared there to carry Lord Muruga.
~Skanda Mahapurana chapter 21
Divine staff of Lord Brihaspati.
Thereupon, the son of Pavaka (i.e. Skanda) was crowned and invested with the power of the overlord of all the spirits and goblins on the banks of the river Sarasvati, Bṛhaspati gave Kumāra a staff.
~Skanda Mahapurana
Gnanastram
Sooran was boiling with anger when all his channels of support got shut completely. So he used his magical powers and took various forms to fight Muruga. Kandhan used his Gnanastram and dispelled his magical illusions.
~Skanda Mahapurana, southern version
Originally answered What are the weapons of Lord Kartikeya?
Bow
Arrow
Sword
Flag
Goad
Vajrayudham
Staff
Mace
Trident
Discus
Conch
This eleven along with Vel forms the 12 weapons of lord Kartikeya
