Matsya Purana — The Advent of Narasiṃha and Hiraṇyakaśipu’s Weapon-Assault
वायव्यं मथनं चैव कापालमथ कैङ्करम् तथाप्रतिहतां शक्तिं क्रौञ्चमस्त्रं तथैव च //
vāyavyaṃ mathanaṃ caiva kāpālamatha kaiṅkaram tathāpratihatāṃ śaktiṃ krauñcamastraṃ tathaiva ca //
“(He also taught/mentioned) the Vāyavya weapon, the Mathana weapon, the Kāpāla weapon, the Kaiṅkara weapon; likewise the unfailing Śakti (spear/power), and also the Kraunca weapon.”
This verse is not about pralaya; it is a technical enumeration of named astras (divine weapons) within a martial/ritual knowledge section.
By cataloguing astras and the idea of an ‘apratihatā śakti’ (irresistible power/weapon), the verse aligns with kṣātra-dharma themes—royal preparedness, protection, and disciplined use of sanctioned power—rather than household ritual duties.
No Vāstu rule is stated here; the ritual significance is indirect—these astra-names typically presuppose mantra-invocation traditions (astra-vidyā) used in consecrations, protection rites, or martial liturgy in purāṇic culture.