After you unlock the final class, one appears as a patron at the bar, where he goes on how an Imperial knight's drive blade is as important as his life, and it's vital for their honor to fight using it and it alone... A moment later, though, he admits he was just trying to sound cool and the truth is that they're too damn heavy to dual-wield with anything.
Etrian Odyssey Untold: The Millennium Girl
In The Millennium Girl, Simon and Raquna enter Frederica's cryogenic sleep chamber from the nearby room. How does Arthur join in? By crashing through the ceiling window.
Some of the response options qualify. You could have the Highlander want to lie down in Frederica's cryogenic pod after meeting everyone, or you could have him eat the Crabapples you got for a quest, in response to your client telling you to hand them over.
In the artbook that comes with the preorder of the game, there's the comic where Frederica needs some real food. When Raquna cooks and everyone digs in, Frederica gets poisoned due to Raquna being a Lethal Chef, and Simon, of all people, is calling for a Medic.
Arthur: It's easy! Just roll it out like 'bam!' then tie it down like 'wham!' and then you lie down like 'oooooh!'
There's an event in the second stratum where a character in the party can Vine Swing. If the Highlander does it, after he gets his TP restored, you have the option to yell! Enemies ambush the party if he does.