Here we see a fool throwing away his life for nothing.
its not really for nothing, sure its kinda BM for him to do it, but for me, i think he did this to show Brian and Climb the witnesses of the 1v1 how much of a gap, a Galactical Gap they are to Ainz. if i remember no one survived the "Tomb Raid" the Empire only knew that everyone who went in ( even the ones that just on the outside as well ), never made it back and assumed that they are most likely dead. they didnt know who, what, and how it happened at the time, all they know that they are dead ( since they never came back. )
( but didnt ainz send the twins on the empire to send a message? ) yep, he did, but its only the empire, not the kingdom. Sure jivnic, paradine and everyone else who stood infront of him when they visited the tomb, knows A BIT of his power, but not all of it.
( but didnt Stronofff knows he strong as shit? ) yup, but even when he told them ( the nobles of the kingdom ) that he strong as hell and this is a BM going against Ainz, he got called a pussy and no one sorta believe him.
If we put ourselves in the perspective of the Empire and Kingdom. the Empire, ( the only country as of this moment, that knows an extent of his power ) they witnessed that Ainz can command these death knights and ancient class demons like nothing. but thats it, he didnt show em magic except when making the death knight infront of em and at the start of the war. he didnt show his absolute best. ( the Ainz and Shaltear fight is a different matter, as far as i know, no country that has been introduced witnessed it as for this moment )
the Kingdom on the other hand ONLY Stronofff knows how much of a threat Ainz is, the Kingdom as whole dont know Ainz at all, and like i said before even when Stronoff told them ( the nobles in the meeting ) they didnt believe him. ( I forgot Brian clashed with Shalltear as well, but he doesnt know if she is connected to Ainz at all, all that Brian knows that she is a separate entity to Ainz and not a comrade. )
[ But arent you forgetting Ainz sent the whole Armada on the lizard men to make a show and threaten them? surely the Kingdom or the Empire knows now how much of a monster Ainz is. ] No they dont, there is no excerpt that i know of, that the Empire nor Kingdom knows a whole f-ing Armada of Ancient Horrors came to a swampy marsh of lizard folks.
so i believe he did this, and made Brian and Climb the witnesses to this 1v1 to show and tell everyone that Ainz is strong as hell, that on top of commanding these adorable baby goats even without that magic he can still be a monster in melee combat (remember that Stronoff is a popular dude since hes the champion of a certain contest where Brian went second place and a significant war deterrent as well ) so if a Warrior/Knight Captain like him, the right hand of The King of Re'Estize Kingdom died not landing a single blow, Nay, not even finishing a single swing, died in one touch in a 1v1 between a SORCERER vs a WARRIOR ( i will emphasize again that they dont know what happened on the Tomb Raid, they dont know that melee combat doesnt work on ainz, well not on anyones current level at least ) He did this for everyone involve or will be involve that even for a "strong" dude like him cant even put a dent on Ainz, theyll have a massive problem on their hands. so if they wanna save their territories they have to play nice with each other, and in turn if we play the scenario forward will make the world unionize to stop Ainz.