"Strewn feathers" are a metaphor for chaos. It can also be a bit of a paradox because feathers are lightweight, and chaos is a serious and heavy matter.
"Sang the heart upon its mantel" in the last stanza is personification.
"See", again in the last stanza, is a homophone, or a word whose pronunciation has double meaning. The poet could mean see as is sight, but also implying sea like the body of water.