Tein, huh? I wonder what the author's going for. It's just hiragana in the raw, and the sound doesn't map onto any word phrases off the top of my head. I guess if you impose a Japanese reading on the Chinese word for mudra (手印), you could get that (手 and 印 as individual words are read "te" an "in" in JP). Or you could use 陰 (shadow/yin) for the 'in', though that doesn't really make any more sense.
Tein'-éigin is a kind of ritual fire lit on Beltane in Scotland to protect against witchcraft. Almost certainly irrelevant, but it was the first thing to come to mind. The 'tein' part just means fire.
I am rambling, oof. Maybe I should get some sleep.