This suggestion of Lucius reminded me of a question I had: should Tethered Magic allow triggering conditions of the same order of complexity as invested devices, thereby essentially creating temporary charged devices, or do they trigger as soon as anything comes into range.
For example, a spell with range Touch would fire when a suitable target touches the object, a spell with range Voice on the first target that comes within that range, etc.
The party pooper in me is inclined to go with that later interpretation, but I'd like to hear your opinions (I don't think we've discussed that here before). While it does limit the virtue a bit, you can still confer benefit and control of the spell to another person, which is non-negligible.
The intention of the Virtue is that the magus can give the magic to someone else to control, but not any special ability to trigger. It goes off automatically. Hunter's Lethal Arrow, for example, kills the first animal it touches. A magus with Tethered Magic could create charged items in the lab, though, which might be closer to what you're looking for?
I'm not sure what you mean. If a charged item designed as a potion has a tethered effect, the target of the spell is not necessarily the person who drinks it. It's the first target that comes into contact with the tether, whatever tether the person who drinks the potion decides to use for the effect. The potion lets the drinker cast a spell, and that spell can be passed on to something else. If you tether a spell to a potion, though, the effect will always pass to the first target that drinks it.