Usually only those of the Lucis Caelum bloodline can brandish the royal arms, but with the king's blessing those joining in an attack with him can also momentarily wield them, as seen in Armiger Chain in Final Fantasy XV, and the climax of the original penultimate boss. The power of kings is also to lend their power to those they are bonded to.

The arms seem to always be proportionate to their wielder, as when the statues of the Old Wall use their royal arms, the weapons are gargantuan. For example, Noctis and Ardyn Izunia can both wield Armiger at the same time with the exact same set of royal arms (though Ardyn's royal arms are a different color), and Noctis can use the Sword of the Father in the battle against Leviathan even if it is in Ravus Nox Fleuret's possession. The weapons have a transcendental presence, as they can be wielded by more than one person at once, essentially being in more than one location simultaneously. He also appears to be the only king without a royal arm, although he can add the Engine Blade to Armiger when using Armiger Unleashed. Noctis is the only wielder of royal arms who is known to suffer a draining effect from it. Even when not in Armiger, the king can use royal arms to warp like with a normal weapon. This state is called Armiger and it cannot usually be sustained for long.

They can even call upon all of the royal arms they have thus collected and momentarily wield them simultaneously, gaining the power to levitate. From then on the wielder can forge the weapon from thin air, and it will appear into their grasp at will no matter where they are. When a royal arm recognizes its rightful wielder, it will become transparent and crystalline and glows before entering the king's body in a flash of light leaving soul crystals glimmering in the air. Only those of the Lucis Caelum bloodline can actually brandish the arms as they were intended, although others can still handle them Ravus was said to be unable to wield the Sword of the Father, but after solidifying his loyalty to Noctis, he wields it as a blunt weapon to fend off the daemons Emperor Aldercapt ushers upon him. Royal arms need not be entombed to be useful to the heirs, as is seen with the Trident of the Oracle and the Sword of the Father it is only necessary for the heir to come into contact with the weapon. Arms left in tombs have been known to have been broken into and stolen and thus thought lost, such as the Tomb of the Tall in Duscae. They are usually left in royal tombs that are hidden around the nation of Lucis in hard-to-reach locations, such as caves, forests, and even on a volcano. The weapons have been preserved for future generations by the monarchs who wielded them, although the exact process this entails is unknown. The royal arms are often especially good for fighting daemons (although in gameplay terms, the royal arms are non-elemental).

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