Can someone explain how 'e' and 'wa' are related in some words / 音便? Presumably the 'e' was originally the obsolete
ゑ since it's in the ワ行.
- 上（うえ） ←→ 上着（うわ・ぎ）
- 声（こえ） ←→ 声色（こわ・いろ）
- 終わる ←→ 終える
(Bonus question: How do you type
ゑ in the IME? I had to copy it from somewhere else.)