You can find Lesmes in the Tower of Crowns after proceeding rightwards from the City of the Blessed Name and up and leftwards from the Grilles and Ruin into the Choir of Thorns. Following the upper path of the Choir of Thorns takes us to the Crown of Towers, where we can find Lesmes in the top left after acquiring Ruego Al Alba and using its special weight of sin attack to destroy the roots.