The speaker is about to be photographed beside an official who hands out prizes, and the mood is uneasy from the start. He calls himself "a simple weak man," which sounds like honest self-doubt rather than false modesty. Standing next to someone with power over awards, he feels small and a little exposed.
The middle lines soften things. "A little grace gathered / at the launch" suggests a brief, welcome calm in the middle of the occasion, as if the event offers some kindness after all.
The ending turns on a metaphor. A launch usually means sending a ship into the water, and the speaker calls his "good ship" nothing more than "what I sing." His achievement isn't a grand vessel or a trophy. It is the poetry itself. The tone ends quietly confident: the ceremony and the prize matter less than the act of making the song. The poem leaves a mood of humility that turns into a modest kind of pride.