What to do? Varka + his sig or zibai?

First some question: you have flins/inefa or nefer/lauma? Gonna guess you have bina and flins (since you want his weapon); you have Durin for varka? Gonna guess yes since you didnt asked "when rerun".

In this case the best option is to wait for the last days of the patch, we should get kit leaks for 5.5 character, which ever it is, linnea or nicole. This could help you decide which of the both are better: nicole a chad support or linnea a lunar crystalize support (we only have sus rumors atm)

First, don't use Faruzan with Varka, he doesn't do much (Anemo) damage, if you have him use Venti, otherwise go for Sucrose.

Besides that, Varka with sig is just stronger than that Zibai team unless you get C6 Illuga and C6 Aino which is highly unlikely.

if you have Columbina, do Zibaui, if you have no Columbina, and plan not to get her, then not zibai, or save for an other character like Nicole or Sandrone.. which are imp much more interestign characters, than Varka with better more useful skill kits, because Varka is nothign but just a boring Anemo Main DPS.. basically Xiao, but with Claymore, that just looks like using two of them copying the Jahoda gameplay partwise of beign able to store PHEC elements into his second claymore to be able to deal basically aside of Anemo also one other element dmg at the same time and beign able to do some crazy high jump attack, that make Xiao look like a fucking jumping beginner, cause it makes him literally leapt like 5+ times the height into the air, compared to Xiaos jumps for plung attacks.. but Varka offers absolut no supportive aspects, hes just a simple mainded main dps character that exists for nothign but just dealing damage only..

However, if you are lackign exactly somethign like that and you pul just for the drip of having a dual wielding character that swings his claymores, liek they are simple 1h swords for him in a way that iot makes him look like a blonde oversized Kirito-Genshin Style , then you are naturally free to pull whatever you like , its just my persojnal bias thats saying, the upcoming characters past Varka will be alot more useful, helpful and interesting, than him and I guess that Nicole will be definetely a character, that most peopel just don't want to miss, where a simple minded DPS character like Varka is rather an easy skip, especialyl if you own already Mavuika/Skirk and plan on pulling also for Zibai, which is basically Geo-Skirk, plus her bestsupport and also new character Illuga is right in her banner too...

You can clearly see by the way how MHY setted up the banners, that MHY wants us to follow fist the Lunar Reaction Meta and brign Lunar Crystallize especially among the people, or they woudl have brought Varka already alot sooner, making him literally one of the first Nod Krai Characters, instead of Lauma + Flins, or woudl have broght him together with Durin directly, where it actually mattered, when MHY introduced the Hexenzirkel buffs, which he receives also (sadly, as it makes zero sense, he should have introduced a new Faction Buff for the "Holy Favonius Knights" to put together the knights and the church of Favonius for a second Mondstadt factino Buff to focus on mostly all other Mondstadt Characters, that effectively have no connection to the Hexenzirkel.. unless MHY plans on makign now slowly but surely everybody of Mondstadt a Hexenzirkel Member over time.. but oh well, thats a different topic now...

If you not pull for Zibai's weapon, thats another reason why id say, just skip both, and go for Nicole or Sandrone later, but you say you have Columbina, then id still go for Zibai, even if you dont want to pull for her weapoln, theres other options to give, her, like Chiori's weapon for example, or that craftable def 4s sword, if you don't have the cinnabar spindle, which looks better on her and is technically the slightly better option also