carefully, attentively, profoundly
倩 centers on a quality of careful, attentive, or profound engagement, often describing a person's manner or appearance. The given meanings point to a refined, deliberate presence.
倩 combines 亻 (person) with 青, which likely contributes the sound and may suggest a refined or clear quality. The exact historical development is uncertain.
A person 亻 beside 青 (blue/green, suggesting clarity or freshness) acts carefully and attentively, like someone handling a delicate, clear object.
For セン, imagine a person carefully counting one thousand (千, せん) tiny details: 千 -> セン, and their attentive focus matches the kanji's meaning.