Hexwraiths are nasty, come in batches of 5-10, magical, flaming attacks that ignore armour.
Most etherials you would need to combat res the hell out of, ie wraiths, spirit hosts, the carriage of magical abilities
Or at the very least use lore of metals blades of aibain I think it is? Don't have the book
Most players with etherials will have them hit your vulnerable units.
Hexwraiths are nasty due to vanguard, and march 18 if general is in 12, also can move through units and hurt them.