That team is good, but I honestly don’t think Ningguang would fit with that team…
If you’re using Razor as your main DPS, then all of your party members needs to become either elemental reactors or supports, since Razor’s playstyle is a “One-man Army”, where he’s the most active member on the field.
From your lineup, Razor, Xiangling, Kaeya, and Barbara is really good, since all of your party members can apply different elementals, which will create many reactions.
Kaeya‘s job is to apply Cryo, where it’ll create Superconduct reaction with Razor, which will reduce enemy’s Physical RES. This is basically Razor’s best playstyle, since his biggest strength is Physical DMG, so you can deal more damage via normal attacks.
Xiangling is one of the best Pyro sub-DPS in the game, especially if you unlocked her constellations. But even without them, she can still deal significant damage using the Guoba + Pyronado combo, and also Overload reactions with Razor.
Barbara‘s role is mainly as a healer, but her skill/attacks can also applies Hydro to enemies, which can create Electro-charged reaction with Razor.
Using this party, always prioritize Kaeya’s Cryo attacks above anything else, since you need to abuse the reduces Physical RES debuff 24/7, in order for Razor to deliver huge damage. After the Superconduct occurs, then you can proceed with other reactions, whether using Xiangling or Barbara.
For Razor’s weapon, use the Snow-Tombed Starsilver Claymore that you get for free from one of the hidden quest in Dragonspine, since that’s his best free weapon. Also, use the 4-set Gladiator Finale artifacts, with ATK%, Physical ATK, and ATK%/Crit Rate/Crit DMG stats (Crit Rate/Crit DMG/ATK%/ATK for sub-stats).
I dunno about your other party members, but if you got either Xingqiu or Diona, then you can also use them as your party member, since their talents are really good for sub-DPS and support.