EÎ

This letter combination represents the sound /ɛr/. It's not very common.
It's found in nouns and adjectives where the stem ends in -eire.

E.g.
to impair, the impairment [Modern English]
to empeire, þi empeîment [Inglish]




Citations:
https://www.etymonline.com/word/impair#etymonline_v_1546
https://www.oed.com/dictionary/impair_v?tab=factsheet#824069

https://www.etymonline.com/word/impairment#etymonline_v_42235
https://www.oed.com/dictionary/impairment_n?tab=factsheet#825017