Multiple followers asked, “Why does cyberware make you vulnerable to thunder and not lightning damage? Does the sound knock screws loose internally? Would lightning damage give it a charge?”
Originally it was both thunder and lighting damage, but that ended up being too much of a drawback, so we ended up choosing one. Why Thunder instead of Lightning? We had a couple reasons for this.
The first has to do with 5e itself. The base game already has multiple effects in which thunder damage interacts in special ways with objects, constructs, and equipment. This helps put the cyberware and robot creatures (which have Thunder Damage Vulnerability) in line with that.
The second has to do with cyber design. You’ve kind of got it on the money. We decided that the average person using cyber would run into problems with electricity more than with powerful sound waves. So insulated, non-conducting metals and wires are a must in modern cyberware in the Nacora Galaxy. Not to mention the power source is actually the biology of the person it’s attached to! So short circuiting it is quite difficult.
Sudden electrical shocks aren’t going to hurt you more than normal, but intense sound waves break up the pieces inside the arm. Advanced machinery like robots, cyberware, and computers in Nacora have a lot of sensitive internal pieces and it’s harder to vibration proof the cyber than to properly insulate it and make it non-conducting.
