The names of these cities here refer to the people who live in them. Alternate translation: "say to the people of Jerusalem ... people of Zion" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here the "hands" are a metonym for the whole person and being physically weak is a metaphor for being discouraged. Alternate translation: "Do not allow yourself become weak" or "Do not become discouraged and so stop working" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-synecdoche]])