quality discussion between 50% warn for sure
the calcs dont consider ias in the tables unless weapon ias and gear ias are considered differently in the formulas, so you just have to do a tiny bit of calculation yourself. breakpoint for zeal with lvl27 fana is indeed 56, so if your weapon already offers 40 ias, you need another 16 (i.e. 20) ias from other slots. e.g. gloves or amu