Up in Arms - Atma and Animus - questions

[Undeadfire]

If we wish to upgrade another Zenith Relic to Atma, do we need to collect 12 items from FATE again?

Yes

While we are upgrading Atma to Animus, can we upgrade multiple Atma weapons at the same time, or do we have to complete one first then move on to the next one?

You can do multiple.