The Jungle Blade was considered to be one of the most powerful swords within the first few days of the V0.3 update..
Before Col was reset and inflation occured, the Jungle Blade boasted an amazing set of stats which was 19 attack and 2 speed. It was stronger than the Frostbite, which made people use it significantly more.
12,500 col was considered a lot at the time, within the newly Col-reset Sword Art Online. The Jungle Blade soon rapidly gained popularity as more and more people got enough Col to buy it, making it one of the most widely used swords by most players around level 20.
Rukiryo soon nerfed the Jungle Blade to a state where it was rendered a sword more useless than swords levels below it. With damage dropped to 11 and speed down 1 the Jungle Blade became unusable, essentially because the level requirement wasn't changed at all.
For reasons unknown, Rukiryo changed the apple stats of the Jungle Bladeso drastically, while common sense would have made the damage different. Players quickly moved on to the Storm Blade and started farming for the Frostbite much more.