The Crimson Binome
Hero
Simultaneously stopping the regeneration of two trolls is a unique thing that the warlord enables which the party could not otherwise do with just a flametongue, in much the same way that casting Fireball is thematically and mechanically distinct from casting Firebolt. You could try to argue that it's all the same, because you're just dealing some amount of fire damage to some number of targets, but the relative amounts of damage and areas of effect are actually important distinguishing details.That's not a unique thing, it's doing a unique thing a second time.
If you just want to generalize, 60% of everything you can do is all the same because it's just dealing damage along various vectors, and 80% of everything is the same because it's dealing damage and/or status conditions. The degree to which you are trying to generalize this would make all discussion pointless; the freedom to use the same sword twice in a round is meaningfully distinct from being limited to using it once per round whenever we care about analyzing the game at the level of complexity at which it is designed and played. It is at least as important as the distinction between Fireball and Firebolt.