Hey Sirhope!

I've actually never had Spirithost, but I can give you some generic advice. Since she is a support, she isn't supposed to be the champion that dishes out tons of damage, but if you want her to be, you can equip attack% artifacts on her to increase her power. 

And although the artifact set bonuses are good, they shouldn't be the main focus. The main stat for the artifacts should be where your attention lies. I would recommend having her tanky and speedy, so boots with speed as the main stat and gauntlets and chestplates with their main stat as HP% should help. I'm not exactly sure how far you are into the game but I hope this helped a bit!

Cheers!