He is a red, jagged sword who is an ancient sword that was possibly created by someone with evil magic who wanted to turn people evil since that who ever holds the Scimitar turns evil until someone hid him in a old temple until the Thriffith and the Goodsword discovered it.
He is pure evil and is capable of corrupting even the most pure of souls, such as Thriffith, Puss and even Dulcinea who Puss believes is the most pure person he has ever met. He wants the blood of his enemies and to kill everyone in sight. He can be sarcastic and hates compliments and goodness. He frequently shouts he will kill Puss and everyone, even the innocent people. He is filled with rage and negative emotion and is not subtle about this, frequently shouting he will kill Puss for imprisoning him.
However, for all the Scimitar's bluster, he is deeply frightened of the dark and is grossed out by sprites climbing all over him with no hands to grasp them.
He was buried in an underground cave and Thriffith picked him up, succumbing to his evil and killing several people and waging war.
He is a sword that grants the user increased agility, speed, strength and gives the person advanced sword skills. In addition to that the sword himself is very strong and can float on its own. He can corrupt anyone, though it sometimes takes longer for certain people. When Puss held him, Puss was able to resist him long enough to imprison him. When Dulcinea held him, it took several hours and the process occurred slowly, first with her killing a mosquito (which she considered evil) and then calling Uli's legs weird and then calling Puss's hat unfashionable. However, she was able to fully resist him enough not to kill Puss as he intended, showing those with pure hearts and strong determination can overcome his evil. He can also only possess people with hands.
He is scared of the dark as shown in Epsiode 10
He was also called "That Thing" in Episode 10 by the Thriffith after he lost all his evil thoughts and stuff.
"That thing controlling me," -Thriffith, Episode 10