Kayamkulam vaal (meaning Kayamkulam sword) is a double-edged sword that was used by the rulers and soldiers of Nair aristocracy (mostly in Travancore), in the Kayamkulam princely state of India. An example is on display at the Krishnapuram Palace Museum in Kayamkulam.
It is said to have been used by the Kayamkulam Rajas in the 18th century. Some Nair families such as Velathandethu house (Pallarimangalam), Padanilathu house (olakettyambalam), Edathitta house Changankulangara (The vaal presented to Valiyakulangara devi temple, Oachira), Thottathil Ellam Valiyakulangara, Oachira are keeping kayamkulam vaal as their historical evidence of family.
- Harikumar, A (5 April 2005). "A window to the past". The Hindu. Archived from the original on 6 April 2005. Retrieved 8 January 2010. The museum has a large number of antiques, which were used by the kings who ruled the erstwhile Kayamkulam State. The most important among them is the Kayamkulam sword. Unlike the common sword, this one has both its edges sharp.
- "Krishnapuram Palace". Archaeology Department of Government of Kerala. Archived from the original on 22 January 2011. Retrieved 20 March 2011.