I don’t know the answer to your specific question, or part of it. There are three branches of government, Legislative, Judicial and the Executive. Congress is but one of the three branches. The way you phrased your question suggests there are four branches with Congress being one of them. Who are the other three you are thinking of?
Congress, in session, can subpoena persons to testify. A person can be found in contempt of Congress but I don’t know if they can order an arrest (I presume they can) but who actually makes the “arrest”, I don’t know.
Interesting question.
I find many people hold Congress in contempt. Who can/will arrest them for us?
The Congress can issue a warrant but it would need to be enforced by the Executive Branch. The Supreme Court can strike down laws and order the Executive to do something or to not do something but it must rely on the willingness of the other two Branches to exist under and honor the rule of law to enforce their decisions.
Simply put all three branches are co-equal and none has superior authority over another. If Congress issued an arrest warrant for Holder, who would enforce it? What if obama and holder simply refused to obey? We would have a genuine Constitutional Crisis and who knows where it would lead.