If they slow you and then kite there is not much you can do. Try to get a slow on them with stagger, moors armor with the stagger set bonus should help, and get to the king up for your run speed boost to help stay up close. If they get too far from you can pop charge to get back in their face. Get in close and they are squishy until they use their evade skill.
Not much a melee class can do against a ranged class with an easy slow, at least that I've figured out so far. Hard class to solo, though not as bad as weavers imo.
If anyone has any suggestions for me other than what I've said please tell me, the above strat doesn't have a very high success rate but its the best I've come up with.
Keeping either the +5% or +10% run speed coffee on will help a lot. If you hit Charge and cannot kill the BA in 17 seconds, note he may hit his 30s evade skill to counter your Charge, then there is not much that you can do.
It may sound grim, but when all hope is lost of hitting him, rather than keep doing the same thing I swap into all of my tank gear. This is where it's best to save all of your cooldowns, for when you are in your tank gear, just try to out last him in your tank gear using your cooldowns and pots. Sometimes the BA will use up too much of their power and won't be able to keep you slowed, when that happens swap back into your dps gear and, if enough time has passed you may even have Charge up again, you'll have your best opportunity to kill him.
If you can get a bleed on him great, but I like to spam Overwhelm and To the King on them to repeat stun them. Audacity will eventually make a stun feel like an interrupt, but trust me it still helps.
If at any time you can get a Stagger on him and have your coffee on then you stand a really good chance of killing him whenever that Stagger debuff is on him.
If you support the Free 2 Pay system, then you can always use an in-combat insignia to counter his slows. It's also possible (not confirmed) that a stun or root pot could possibly provide you with 10s of slow immunity, but I'm not sure.