WA vs Primary stat

You can compare it to 15 luk out of your total luk, or 5 luk out of your base+mw+regular bonuses.

Like how for me it'd be 5 str out of ~1000 (830 base + 170) or 8 str out of ~1600 (62% str). It works out the same either way, you multiply both numbers by the same thing (%stat).

What Stereo is saying is that you should compare the ratio 5luk/(base+mw+regular) to 1atk/totalAtk, or 15luk/totalLuk to 1atk/totalAtk. And it would be the same thing.
This doesn't give you directly the luk/atk ratio, though.