Right, I agree it is fuzzy. I just think, from an ethical standpoint, it is better to think of them as mines that have more mobility. Reasoning from the other end as projectiles which are slower or have more guidance seems to invite too much optimistic thinking about the level of control. That the victims will be as intended rather than quite indiscriminate and unpredictable.

I realize there is a full, multidimensional continuum here.

On one end are directly-aimed weapons that do their damage while still being aimed by the operator. Their risks include collateral damage limited to things like aiming errors, effect radius, or continuing down-range beyond the target.

Further out are messy things with more active guidance that can turn and seek the target and potentially go off course. But their time to target is still quite limited and more or less being observed by the one who fired it. The risk expands with its potential "cone of maneuvering" and travel range.

Then you get into these things with long dwell times and autonomy where the eventual targeting event happens without supervision and is greatly affected by things happening in the environment which the operator cannot have really predicted nor controlled for. The longer time in operation increases the risk not only from wandering/guidance but from how much the environment can change before it performs its final targeting event.

Another example in this category could be chemical and biological weapons. There is a lot more uncertainty in the targeting effects due to the way it disperses in the environment.