Arm/Hand Weakness
Your hands and/or arms (Roll 1d6: 1–2 Hands, 3–4 Arms, 5–6 Both) get weak due to muscle tone or neurological failure. All Strength attack rolls, ability checks and saving throws have a −(IE) penalty to hit, and all damage is divided by (1 + (IE)), rounding up.
Real-world Examples
Arthritis, Myopathy, Tendinitis, Amyotrophic Lateral Sclerosis, Carpal Tunnel Syndrome, Cerebral Palsy, Multiple Sclerosis, Down Syndrome
Assistive Options
Devices or weapons that strap onto the forearm can assist with hand weakness, as can a device that provides leverage to reduce the strength needed for operation by substituting distance. Be creative!
Magical Assistance
Magic items that increase strength like Gauntlets of Ogre Power or the Belt of Giant Strength items can assist with this but cause excruciating pain if used more than an hour per day, requiring a Constitution check equal to the magical Strength − 5 or take one level of exhaustion per minute after. An item that increases Strength by a specific amount should consider your initial strength to be 7 − (IE).