The Javelin (also called the Spear) is an essential tool acquired in the middle of Phoenotopia and Phoenotopia Awakening. Gale obtains it from some rescued Daea soldiers after dispersing the Daea Guard Horde. As its name implies, the Javelin is a wooden spear that can be thrown like a projectile.
Although it can damage enemies, the Javelin's primary purpose is to help with platforming, as it will stick to any wall it hits and can be used as an artificial platform, making it easier to reach areas Gale wouldn't be able to get to on her own. Many parts of the Prince Tower require the Javelin to navigate, and several areas afterwards (along with some secret areas) also make it necessary to use.
It is possible to enhance the Javelin's power by obtaining the Ki Spear Technique Scroll from Aella as a reward for restoring her memory. Said scroll enables Gale to charge the Javelin with Ki so that it will explode on contact with an enemy, or manually detonated after it has been thrown.
This ability is similar to Bombs, though with the additional benefit of not hurting Gale as well. This makes the Javelin very useful against enemies that must be defeated long-range, as well as rocks and barriers. If a charged Javelin hits a wall, it will slowly lose its charge and revert to a non-exploding Javelin.
The Javelin is also the Kobold General's weakness, as it's the only weapon that can pierce through his defenses, though when he lowers his force field to charge up his special attack.