What is the meaning of てさえも?

Question

These are lyrics from a song called 秘蜜～黒の誓い～

地の底へ堕ちてさえも
誓いの楔を絡め合って
許されない罪を抱えていく

The てさえも sounds a lot like a concession as in ても, but I could not find any grammar explanation about that use. I'd like to know if I am correct and if that is a common use.

Answer 1

Yes, てさえも/でさえも is a stronger version of ても/でも. While ても/でも does not necessary have to be translated using "even", てさえも/でさえも has a strong sense of "even".

• 1時間読んでも分からなかった。
  I did not understand (even) after reading it for an hour.
• 1時間読んでさえも分からなかった。
  I did not understand EVEN after reading it for an hour.
• 知らなくても大丈夫です。
  It's fine if you don't know it.
• (見なくていいどころか)知らなくてさえも大丈夫です。
  (Not only do you not have to watch it) It's fine even if you don't know it.