扌 is the hand radical 手 in left-side form. It marks 援 as a manual action, joining 拉抓持拽 - verbs of grabbing, pulling, and holding. Help in 援 is concrete: a hand reaching out and taking hold.
爰 supplies the sound yuán directly. It depicts a hand passing a stick down to another hand - already a help-image on its own. The same phonetic powers 缓暖媛, all sharing the yuan / nuan reading.
