PRI-ARMs, often shortened to PRIs, are weapons obtainable only via Foundry once the function to craft them gets unlocked at level 81.
In essence, PRI-ARMs are enhanced 5★ versions of specific 4★ weapons. A PRI-ARM possesses an extra weapon skill and while the skill effects are generally similar, the PRI-ARM grants higher bonuses and may have battlesuit-unique buffs that the base weapon does not. As a base 5★, all PRI-ARMs have higher stats than their 4★ counterparts.
To first unlock a PRI-ARM you need to have unlocked its base 4★ weapon in the collection. Divine Keys need to use a level 50 tuned version of the Divine Key in crafting but other PRI-ARMs can be crafted with a level 50 weapon of a matching weapon type, allowing you to keep the base weapon.
To craft a PRI-ARM, you need one level 50 weapon and the following materials:
Upgrading a PRI-ARM doesn't consume any usual upgrade materials such as Honkai Cubes and instead requires the following:
- Lvl 50 cap -> Lvl 55 cap: Einstein's Torus ×100, SC Metal-H2 ×100, Nanoceramic ×30, and Coins ×350,000
- Lvl 55 cap -> Lvl 60 cap: Einstein's Torus ×100, SC Metal-H2 ×150, Nanoceramic ×45, and Coins ×500,000
- Lvl 60 cap -> Lvl 65 cap: Einstein's Torus ×100, SC Metal-H2 ×220, Nanoceramic ×60, and Coins ×650,000