The speaker treats loss as a skill to be rehearsed, as if grief were something you could get better at with repetition. The title, "In practice," plays on this: it means both "in reality" and "while practicing." The tone is wry and self-mocking. The speaker calls himself "lousy" at it, and compares himself to a fool who has won the king's favor yet carelessly leaves his belongings in an open grave. Favor and ruin sit side by side, and nothing is treated as safe or kept.
The last lines shift to a quieter, more everyday scene. People finishing their drinks leave the pub and head home. Calling them "the murderers of a pint" is a joke: they have killed their drinks, and the phrase also brings death back into the picture. The word "strange" suggests the speaker watches this from the outside, a little detached. The mood is dry, darkly funny and a bit lonely, with ordinary life carrying on while the speaker keeps thinking about what slips away.