Source: Standard literature
Sérapéṅdiya is the name of a Sinhalese mythical bird. It often features on Sinhalese art.
Sometimes only the head is shown, as is the case on the guards of kasthāné swords. In that case the sérapéṅdiya can be distinguished from the very similar looking makara (mythical sea monster) and siṃha (lion) by its beak: sérapéṅdiya beaks have a point that curls downwards and inwards. Those of makara tend to turn upwards, while those of siṃha end in a small S-shaped scroll.1
Sérapéṅdiya grip on a Sinhalese knife.
Sold by Mandarin Mansion in 2017.
A Sinhalese kasthāné hilt with two sérapéṅdiya and two makara heads.
Sold by Mandarin Mansion in 2020.
1. See Ananda K. Coomaraswamy; Medieaval Sinhalese Art, Pantheon Books, New York, Second Edition of the 1908 original, 1956. Page 83. Also see P. E. P. Deraniyagala; Sinhala Weapons and Armor. The Journal of the Ceylon Branch of the Royal Asiatic Society, Volume XXXV, No. 95, part III. 7th December 1942. Pages 112-113.