Once Is Not Enough: With the regenerative capabilities, smart cardiovascular nets, auxiliary hearts, and suchlike they engineer into people these days, you should be mindful of this trope, aversion of Only a Flesh Wound notwithstanding. That goes doubly for races like the kaeth, whom nature has equipped with a particularly tough and redundant biology. Check, don’t assume.
As a side-note, Imperials are in a much safer legal position than Terrans when trying to avert this one, when it comes to self-defense. The Curia is of the view that any law that requires you to act out bad horror-movie cliches is a bad law, and so, if you’re justified in having to put someone down, you’re entitled to make sure they don’t get back up.