Told in a few clipped, strange images, "Discharged" feels like a record of a bad stretch of life, though the poem never says exactly what happened. The word of the title could point to a release from hospital or service, or to something drained or let go, and the poem leaves that open.
The speaker seems to be in a fragile state. The water is "thin and harmlessly sad," as if even the basics of life have gone weak and quiet. Then the book on mortality "hit back," which suggests that thinking about death stopped being abstract and turned on the reader. The line about living in the dangerous part of town may be literal, but it also reads like a description of the speaker's own state of mind.
The last image is the sharpest. Bleeding hope to ease the pressure is like emptying something out to survive, yet the comparison to "a bed full of guns" makes that relief feel unsafe. The mood is tense, numb, and wary.