It depends on your funding and gear preferences for your class.
Unless you plan on wearing the whole level 140 set, you don't need to put any points into your secondary stat. Scrolled high level stuff like htp and czak among many others will provide your second stat for you. Just have some %all stats. My shadower has almost 300 dex with a base of 4 dex and 2 pieces of empress gear.
If you're really funded, you can get lots of %all stats on all your other gear and still be able to wear the empress set with 4 dex/luk.