I often prefer the KISS method. The simpler (and less time consuming) the better. I remember a few suggestions a long time ago to just grab a couple of rock of a good size to hold in your hands while out on a run. Run with them until your arms are tired, then drop them (carefully, don't want to break a toe 😉 ). I also occasionally will take 10-15 pound dumbbells, one in each hand, and swing my arms like a sprinting motion. Other than that, maybe occasional pushups (primarily chest and triceps), dips (shoulders and triceps), or pullups (usually assisted in some way, upper back, biceps, forearms). In general, though, I actually do very little upper body work and, while my arms aren't big, they actually tend to be very well toned when I'm in good running shape. Even if I haven't done any specific arm strengthening exercises. Remember, toning is more about burning the fat off the muscle than building muscle.
Most of the exercises I listed, especially the first two, are very running specific. Seeing as most of us are interested in our goals primarily as a way to improve our running, those running specific workouts are usually the ones that produce the best results.