Hey. I main a demo lock actually. I normally like to partake in duels or 2v2 arena and that’s as far as my BFA PvP experience goes.
I see you are seeking advice on how to beat fury warriors in particular. Honestly if its a 1v1 situation or a duel against a fury warrior as a demo, there’s really no chance of you winning. Not only is their healing something that you would have to overcome, which is pretty hard to do especially since our damage is pretty bad outside of cooldown(s), but their mobility and slows are something that would be of a counter to us.
But if you generally want to know where a good brunt of your damage comes from, its your demonic tyrant (as many other previous posts have mentioned). Other than that, a lot of your damage typically comes from your pets (mainly dreadstalkers and fel guard). The spec is designed poorly right now imo. Having your significant damage source come from a pet that can easily be avoided is not fun especially when its really predictable and you have no other damage options that could provide enough sustained pressure.
As for the gear (artifact pieces), I’d highly recommend having atleast 1 Baleful Invocation (having more than 1 would be nice as well as it stacks) and Supreme Commander ( this one stacks as well and can give you a nice boost of intellect after your tyrant expires for more potential damage). The rest are up to you, depending on your style of preference as I would say there aren’t really any ideal options for the spec. Hope this helps. Good luck!