ME3: Thessia and Kai Leng (Spoilers)

[Grygor]

Ignoring the utter impracticality of using a sword in a universe like ME. I can understand omni-blades, since they're secondary CQB weapons, but forgoing guns altogether? That's just stupid.

Except he doesn't forgo guns altogether. Just like Cerberus Phantoms, he has a firearm of some sort integrated into his arm.

Never noticed that. I'm sure that thing would've come in handy in situations like taking out the Salarian Councilor. Or shooting at Shepard rather than trying to run at him and get his ass kicked as a result. Or taking Shepard out from behind when he and his teammates are (very conveniently) looking elsewhere. The only reason I can think of for using the sword like that is because he must think it's "so coo", as the OP said.

He does try to assassinate the salarian councilor with it, at least if there's someone alive to foil him. (I don't have any playthroughs where both people who can save the councilor are dead, so I can't say for sure in that case.) Sadly, it's not exactly a fast-firing weapon...