There was a novel I read back in the 90s (I’m pretty sure) about a guy who fought using a weighted cloak or cape. There’s very little I remember about it beyond that. He didn’t take the cloak off in the cloak-and-dagger style, but rather used it kind of like a whip from his back and shoulders. Anyone ever heard of it?
If just_happen_to_know comes back, I'll yield the answer, but The Shattered World by Michael Reaves was identified in the comments and confirmed there was well.
A thousand years ago, the world was broken in a great cataclysm; now people live on the fragments, flying between them in ships made of the skin & bone of dragons. The book follows the interweaving stories of a thief, a couple of wizards, and various others as events are set in motion that will take them on perilous journeys to the far reaches of the world with far-reaching consequences.
The "cloakfighter" is named Kan Konar.
There's a sequel with some of the characters including Kan Konar called The Burning Realm.