An armblade is a magic weapon that attaches to your arm, becoming inseparable from you as long as you're attuned to it. To attune to this item, you must hold it against your forearm for the entire attunement period.
As a bonus action, you can retract the armblade into your forearm or extend it from there. While it is extended, you can use the weapon as if you were holding it, and you can't use that hand for other purposes.
If a weapon has the Thrown property, you can throw the weapon to make a ranged attack, and you can draw that weapon as part of the attack. If the weapon is a Melee weapon, use the same ability modifier for the attack and damage rolls that you use for a melee attack with that weapon.
A Versatile weapon can be used with one or two hands. A damage value in parentheses appears with the property. The weapon deals that damage when used with two hands to make a melee attack.
If you hit a creature with this weapon, you can force the creature to make a Constitution saving throw (DC 8 plus the ability modifier used to make the attack roll and your Proficiency). On a failed save, the creature has the Prone condition.