Finn's swords

Finn's Sword is the sword that Finn sometimes uses when he is fighting.

Gold Sword
Finn's original sword was his favored weapon through most of seasons one and two. The blade was made of gold, but was dented, chipped, and dirty due overuse and lack of proper maintenance. Its hilt was black with some worn leather grip-straps, and a red stone in the pommel (possibly a ruby). When the Businessmen were working for Finn and Jake, they polished the sword and sharpened the blade.

In the episode "The Real You," the sword passed through the Bubble Creator, becoming a four dimensional sword. However, when Finn used it to destroy the black hole he had made, the sword was destroyed.

"Root" Sword
After the destruction of the gold sword, Finn started using a new sword with a twisted, root-like hilt as his primary weapon. He obtained this sword in the baggage compartment of the train in "Mystery Train." He then used it in the beginning of "Belly of the Beast" when he fights the Giant and also used it in his battle with The Lich.

Trivia

 * If the stone in the pommel is a ruby, then it maybe a possible reference to Fionna's sword, which is made of ruby.
 * In real life, a sword made entirely of solid gold would not be practical, as gold by nature is relatively soft and malleable, which wouldn't be good for intense combat. Gold is also a very heavy metal. It's possible that it is a gold alloy, or gold plated.
 * The sword may in fact be enchanted. As seen in episodes "The Silent King " and "The Eyes ". It has the ability to deflect fire and ice magic, respectively.