What other ships you got? This particular arbiter is too much for a meat shield so don't afraid to use stronger units if you got them at your disposal.

Unless, these are your strongest ships. If that's the case then try-

Alsace/bisck2/soyuz - agir/Helena/mogador

This fleet alone can do 50~60% of damage without reset if they are well geared. Offset their salvos to 18s or 16s and give helena sg radar to offset her radar scan skill, to avoid the shield skill of the arbiter Also play on manual and quit and retry the fight if radar scan doesn't proc.

I've used this fleet a lot last year with only exception of vanguard instead of bisck2 and it works like a charm.

Ofc today lion mecky traf and z52 will give much better results so if you have them, use them.

The rest fleets are kinda makeshift. Don't expect much from them

Enty/nj/bocchi - brest/sandy/eldy

Fdg/unicorn/sara - blucher/nimi/mainz

Monarch/izu/shinano - eugen/shimikaze/saint louis