After a bit of searching, teh Department of Education maintains it's own law enfrcement branch through the Office of the Inspector General. These Special Agents are tasked with investigating crimes that fall under the education laws, like civil rights violations, fraud, theft, etc. These are fully sworn federal leos, graduates of FLETC. As such, they can be armed.
That said, I have to agree thatI don't understand why every federal agency has it's own enforcement branch with armed officers/agents. Why not just increase the size of the big boys (FBI, US Marshall's, etc.) and expand their authority to cover these areas. Seems to me all of this duplication is a waste of tax dollars...