what is War Emergency Power ?
I found it under settings> controls> buttons> engine
I take it you're talking about a Key Assignment.
I don't have that particular one which makes me think you might have installed an add-on with an installer that was smart enough to add a Key Assignment. Still find that hard to believe, though.
War Emergency Power is usually available in combat aircraft. Engaging it gives you more speed if memory serves, but is only meant to be used for brief durations.
Maybe they equip today's airliners with WEP because of the war on terror?😀