If i were you I wouldn't spend my SKB4 on Infinite Blue, not because it's not good, but because you won't use it very much at higher levels. For example PT (Phoenix Tower) requires somehow a Leech sword (70 yellow) for more chances to survive. If i were you i would make the 65 Yellow Axe Winged Aurora Blade, which is so good for it's proc. Then get orange leech sword which you will turn in Yellow at level 70. This helps for ACV boss solo-ing as well.
1) If you can solo World Bosses like Surbora or aschen or any other boss that drop Grade A Scrolls, it's cool to forify your Warlord Legacy as much as possible. ( Not more than +9) If you need to buy your scrolls, don't bother to +9 or higher it. Just get that awesome 70 set and +9-15 it.
2) Try to get 65 yellow Winged Aurora Blade, 66 leech sword, and the most important imo, for a good dps WL get hte 68 gun. (+55% crtical damage) - Bahado Devilish Gun- if i remeber well. Unfortunately it's not tradeble, so you will need to craft it, the closest Gun sprite is 66 Cenia, which is super rare.
3) For Dual Wield use General talent setup.
4) 15% attack speed is good, but to be more epic get a -30 % deffence equipment for sprite.
This are the things i could suggest you to do! Good luck!