What Is Ronan's Hammer?

The Universal Weapon, also known as the "Cosmi-Rod", is a Kree war-hammer and many used by the "Public Accusers" (Accuser Corps) of the Kree Empire and of the Kree race. The alien supervillain Ronan the Accuser wields the most powerful one.

How does Ronan hold the Infinity Stone?

Rather than giving the Power Stone to Thanos, Ronan uses it for his own nefarious goals in Guardians of the Galaxy. Grabbing the Power Stone from its housing, The Orb, and struggling to contain its power for a time, Ronan places the gem in his weapon, the Cosmi-Rod, allowing him to use its power safely.

How powerful is Ronan in the comics?

Ronan later joined the Accuser Corps, who are the Kree equivalent of military governors and jurists, and his rise through their ranks was extraordinary; he eventually became the third-most powerful being in the Kree Empire. The Supreme Intelligence ultimately appointed him "Supreme Accuser of the Kree Empire".