Your also not likely to win without a super in that situation anyhow. If you melee a Bladedancer and get Flame Shield you stand a good chance of winning the fight. And that's if they decide not to Razors Edge you. Challenged a Defender in His bubble has never been a good idea. Barrier melee only stays active for a short time you also need a melee kill for it to activate not just a hit. So that means you already got into a fight and have low actual health. If you come upon a Bladedancer within the amount of time that Force Barrier is still up you probably don't have full health and are likely to die.

Of course you'll lose that fight. I don't go in Wards. Smart players avoid them like the plague. Destiny isn't full of smart players though... And Barrier melee lasts between 10 and 20 seconds depending on perks and if you rock NBP. Razors Edge is extremely small and easy to strafe or full hop over, unless there's a low ceiling or you're in a tunnel, which is arcblader territory.