Ugo and Bertrand are just hired assassins, trekking across the countryside to schlep Emily to Tuscany. They might seem like Tweedledee and Tweedledum, but don't be fooled: these guys drop hints that they're trained killers, happy to do Montoni's bidding at the drop of a hat.
Bertrand in particular relishes talking about his former exploits, though he's a little loose-lipped around Emily. "He fell and was dispatched in a minute," Bertrand casually throws out there in the middle of a conversation (3.5.95). He's totally comfortable killing someone without any real reason. These aren't guys we'd want to be around in a dark room, let alone the middle of the woods.