++Weapon:
At first when he is talking about his past to Rin it shows a flashback of him carrying a Sword. He was actually pretty skilled with it.
Jaken also uses a staff as a weapon, called the Staff of Two Heads. It has a woman on one side and an old man on the other. Here are some of its powers. The Staff was given to Jaken by Sesshoumaru.
Jaken can use the Staff to locate Sesshoumaru's Fathers grave. If its on the right track the Man will make a noise but if its farther from the grave the lady will scream. Freaky if you ask me =P
Jaken can use the Staff to make fire and I think also control it. He uses this power the most.
In a later episode, He uses it to make water while tapping it on a scroll of some sort.