This skin is available to purchase in-game, when in store rotation. The Sentinels Of Light Knife is sold as a individual skin for 4350 valorant points or as a part of the Sentinels Of Light bundle for 8700 valorant points.
This skin is upgradable. There are different levels that changes the look of the skin, it costs 15 radianite points to unlock each level. The different variations can be seen below.