It resembles a two-sided hammer attached to a long red hilt.
In "Zombie Invasion", Thoren used the Earthquake Hammer to fight a horde of zombie pirates.
#124: Attack of the Centaurs
Thoren can be seen wielding his hammer when his cousin Sky calls the Specialists and Paladins to action, however, he is not seen using it until towards the end of Issue 124. There, he uses it to crack apart the ground to stop the Centaurs in their tracks as well as protect Daphne and Breeze from their fury. It is thanks to Thoren's actions that the Centaurs fall into the Winx's trap, allowing for the six fairies to successfully blast them back into the Legendarium with a powerful Bloomix Convergence. In this instance, Thoren calls his weapon the Seismic Hammer.
Upon striking the ground, the hammer is capable of creating powerful seismic waves.