I saw a report from a construction safety group that said dropped tools cause a lot of site accidents. They had data showing how often small items fall from pockets on sloped work. Your wrench story is a perfect example of why they push for tool belts or tethers. Even a light tool can gain speed and hit someone hard from up high. It feels like a hassle to strap everything on, but it really does prevent worse mishaps. Glad your situation was just a spilled coffee and not a real injury.