I suppose you could use it on yourself, but you'd be wearing all +smn magic gear, which sucks, and losing the benefit of stacked haste which sucks more. 23% gear + Hasso + Hastega is as good as 92% double attack.

I'm thinking the practical application of Ifrit's favor will be in a Emp Weapon WS situation that does not normally get the aftermath bonus. I'm guessing Myrkr doesn't double attack though. 120% MP anyone?