@CognitiveShadow gave me this idea, so thanks to them. In this scenario, we’re assuming Taln has enough stormlight to last throughout the fight. We’re also assuming that Rashek has the base 16 metals, but no ettmetal (yes i call it ettmetal) or atuim shenanigans (besides his atiumminds). Below are the notable attributes of each.
Rashek: sliver of preservation, full mistborn, and full feruchemist. A savant in most era 1 metals. Also might have had hemalurgic spikes of an unknown charge. His most useful abilities are probably his compounding. He can compound his zinc and steel for insane speed, his pewter for strength if needed, his chromium for luck, his gold for regeneration, and he might (that’s a very dubious “might”) be able to imbue himself with so much investiture via nicrosil compounding that he can flat out resist a shardblade/honorblade. It’s also notable to note that Rashek is extremely overconfident.
Taln: herald of the almighty, holder of the stoneward honorblade.not much else to say. We don’t know exactly how skilled he is with his surges, but we can assume he is very skilled. He is also vey skilled in unarmed combat, being able to kill tens of fused and hundreds of singers with his bare hands and some help of ash. In this fight, we’re assuming he has enough mental stability to fight, and that he has his honorblade.
overall, I’m voting Rashek, but i can see an argument for either side. (Yes, i know taln is technically immortal. If he kills or incapacitates taln’s body that would count as a win.)