The biggest possible flex of course if having reflective darkened (blued or blackened) steel.
Like in this reproduction you may have seen from Christopher Gilman (Diligent Dwarves on YT and Blogpost).
Adam Savage got the privilege to try it on some time ago.
I've gotten a couple questions about wether this kind of armor was actually used.
Yes it was!
Both in war and tournaments.
Many of these suits of armor have copious amounts of articulation damage, scratches and dents that can't quite be appreciated unless looked at up IRL.
The Everdark Sovereigns is the result of Wylder's ending where he revives the other Nightlords, and Deep of the Night mode is the result of Ironeye's ending where he gets his endless night and stronger enemies