The weapons associated with Lord Vishnu are:
Kaumodaki – Mace of Vishnu. It can destroy anything in the
universe.
Sudarshana Chakra – The discus of Vishnu. It contains the power
of sun. It flies on the command of Vishnu and it can be only stopped by Him.
Sharanga – the bow of Vishnu
Nandaka – the sword of Vishnu.
Narayanastra – arrow. Can create a shower of arrows. It
could only be used once. Vishnu blesses his devotee with the arrow.
Vaishnavastra – arrow. Infallible. It could only be used
once. Vishnu blesses his devotee with the arrow.