Source Starfinder Armory pg. 94
System Arm
Bone blades are weapons built into undead arms that are then grafted onto their recipients. The blade can be retracted into the limb (making it impossible to notice without a careful inspection, scan, spell, or similar ability) or extended from the wrist for combat. Extending or retracting a bone blade is a swift action, and you can’t use the hand of the associated arm to hold anything or perform fine manipulation when the blade is extended. A bone blade cannot be disarmed, but it can be sundered. When you regain Hit Points (whether through first aid, magic, or natural healing), the blade regains the same number of Hit Points. If destroyed, a bone blade regrows in 24 hours.
Standard bone blades are one-handed simple melee weapons with the operative weapon special property. It is possible to have a more complex heavy bone blade installed, which changes the bone blade into a one-handed advanced melee weapon. These heavy bone blades are not operative weapons, but they deal more damage (see the Bone Blade table). There is no difference in cost between standard and heavy bone blades, but the decision between them must be made when the bone blade is installed and cannot be changed.| Model | Standard | Heavy | Critical | | Mk 1 | 1d4 S | 2d4 S | Staggered | | Mk 2 | 1d8 S | 2d8 S | Staggered | | Mk 3 | 2d8 S | 4d8 S | Stunned | | Mk 4 | 5d8 S | 7d8 S | Stunned | | Mk 5 | 5d10 S | 7d10 S | Stunned |
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