Sources

Dail an Easaich: Dwelly [but derived from MacKay]

The Ordnance Survey namebooks list an alternative name of Dalnessie as DAILNAHEASAICH, with an alternative form as Dail na h-easaich.  This is possibly a rationalisation by Rev. Joass however.

Dwelly gives easach as both masculine and feminine (and as an adjective).

Easaidh masculine appears to exist in toponymy.