The topic of this metaphor is that because of what the Spirit did, Amasai had special powers. Possible images are 1) the Spirit came over or came on or covered Amasai like a garment, thus giving Amasai special powers. Alternate translation: "came over Amasai" or "took control of Amasai" Or 2) the Spirit covered himself with Amasai and so acted through him. (See: [[rc://en/ta/man/jit/figs-metaphor]])
These phrases share similar meanings. The idioms "we are yours" and "we are on your side" both mean that the men support David. Alternate translation: "We are devoted to you, David. We support you, son of Jesse" (See: [[rc://en/ta/man/jit/figs-parallelism]] and [[rc://en/ta/man/jit/figs-idiom]])
Here the word "peace" refers to prosperity and well-being. The word is repeated to emphasize great prosperity. Alternate translation: "May whoever helps you greatly prosper" (See: [[rc://en/ta/man/jit/figs-doublet]])