This skin is available to purchase in-game, when in store rotation. The Tethered Realms Knife is sold as a individual skin for 3550 valorant points or as a part of the Tethered Realms bundle for 7100 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.