For the rogue, if you have a 50% chance of hitting and are using RTB 5 you do more damage with a ranked +6 ele weapon than a +5 ranked VVS Ele weapon. Increasing the hit or RTB level just increase how much better the +6 weapon is.
As for Fatal Blow, the weapon being ranked is enough to get your bash to stun. Even if you can't get a ranked weapon a +6 VS Ele weapon is cheaper to make than a +5 VVS ele weapon and will do more damage with skills while providing seeking damage.
