There are choices you have made in your build. With those choices it means you are going to be good at some things and bad at other things.
Some people you will curb stomp others you may not and sometimes you will be the one who gets stomped.

I am not going to comment on bat but just as one of the many options for a way to beat a champion paladin if your build was different. But guess what then you would have weaknesses in other areas for some of the strengths you may gain.

Could there have been other things on my end at play certainly! But ill show the part that's important!

Batman yells 'Help! I'm being attacked by the Imperial Warlock!'
the Imperial Warlock: Intruder! Intruder! Batman is raiding the Cabal!
Batman yells 'Help! I'm being attacked by the Imperial Assassin!'
Batman yells 'Help! I'm being attacked by the Imperial Prelate!'
The Imperial Prelate mauls Batman.
The Imperial Prelate wounds Batman.

Batman whirls an eagle inscribed staff to strike you before you can react!
You yell 'Help! Batman is batting me!'
Batman's quick strike MUTILATES you!
Batman has a few scratches.

Batman starts aiming at you!
Batman has a few scratches.

You say, 'I'm Batman!' *** Totally should have said this!!!

You bring a thorn-encased ironwood shillelagh around with bone-shattering force!
Batman can no longer find the strength to wield an eagle inscribed staff.
Your bone-shattering blow wounds Batman.
Batman has a few scratches.

The Imperial Warlock's slash mauls Batman.
The Imperial Assassin's slash mauls Batman.
The Imperial Assassin's slash mauls Batman.
The Imperial Prelate's slash mauls Batman.
The Imperial Prelate's slash wounds Batman.
You dodge Batman's punch.
You parry Batman's punch.
Batman's punch EVISCERATES you!
Your piercing venoms misses Batman.
Your crushing force decimates Batman!
Your crushing force devastates Batman!
Batman is covered with bleeding wounds.