In the first stanza of this poem, the eagle is personified as a king. He does not have claws, but hands, so we're to see him as a symbol of a person. He lives "close to the sun in lonely lands"; his closeness to the sun associates him with its power and dominion over the world. The "lonely lands" show him as a lonely figure, as kings are (responsibility and leadership are lonely jobs). He is "ring'd with the azure world," showing him again alone under the canopy of heaven. But...he stands. Standing is a posture of power. Compare this to the next line--the first line of the second stanza--in which "the wrinkled sea beneath him crawls." He "stands"--he has dominion--but the sea "crawls," a personification of the sea which likens it to lowly people at the feet of a king. "He watches from his mountain walls" like a king from a castle; castles were almost always built upon a hill or mountain to create additional natural defenses against attack and greater surveillance abilities. Finally, "like a thunderbolt, he falls" likens the eagle to another unstoppable force of nature: lightning. Eagles dive at speeds upwards of 150 mph to catch their prey; this simile means the eagle is fast and deadly on the attack.