Agidez is a less common, more formal word for 'sharpness' or 'quickness of mind,' derived from 'ágil' (agile). It carries a sense of mental acuity and readiness.
In the song, it's used to describe the king's state: "El rey esta solo en su agidez" (The king is alone in his sharpness/acuity). This suggests a king who is mentally sharp and aware, yet isolated in his thoughts and perceptions, making his solitude even more poignant.
Ana Tijoux, a Chilean artist, brings us "El Rey Solo" [The Lonely King], a song that really makes you think about power and isolation. The lyrics paint a picture of a king sitting alone, timidly, in what feels like a "jaula de monos" [cage of monkeys]. Everyone around him is just waiting for their chance at the throne, which is described as "gastado por años de codicia" [worn out by years of greed]. It's not a pretty image, with its "marmol jerárquico y de madera egoísta" [hierarchical marble and selfish wood].
What's fascinating is how the king's role, which he "nunca quiso" [never wanted], is seen by others as an "ofrenda" [offering], a "flor dolorosa" [painful flower]. He feels incredibly alone, but no one sees it. He's just watching, waiting to see "Quien sera el que tira la primera piedra" [Who will be the one to throw the first stone]. The song really highlights the hypocrisy and betrayal, as those who once offered a hand later "afilaron los dientes" [sharpened their teeth]. The king's crown is described as "añeja y amorfa" [old and amorphous], filled with power but also with a "podrida matriz" [rotten matrix]. He feels surrounded by "animales perversos" [perverse animals] who only want greed. It's a powerful and somewhat tragic look at the loneliness that can come with power, and the madness it can bring, as the king eventually declares, "Yo estoy descuerdo, ustedes han enloquecido" [I am sane, you have gone crazy].