In a real life and death situation...it's difficult to fight.
So perhaps the Klingons are given inferior bladed weapons so that they would be better fighters? If they can manage with that curved double-hander, they are tougher than anybody else!
Alternately, the fighting banana is used because it is a superior defensive weapon. It offers multiple handguard options, most of which are painful to the attacker while adequately protecting the defender. It is good at catching swung blades of all sizes, as the two-hand grip can resist the sheer force of a broadsword swing, while the extensive reach helps deflect attacks by more agile blades from a number of directions and angles without requiring the defender to maneuver the defending blade much.
The offensive capabilities may come as a pure bonus, then. Note how the historical Sword of Kahless had even more barbs and spikes to disrupt the forward cutting surface and augment catching action! Use of two-hand blades makes use of shields impossible - but in this case also unnecessary, except against ranged weapons. If Klingons didn't believe much in slings and arrows (just like they strangely avoid modern ranged weapons), then this form of defense would be an obvious choice.
It's only when the attacker is exhausted that the Klingon warrior releases his hold of one end of the weapon and swings it in a deadly arc...
Timo Saloniemi