The Cubic Hammer is a weapon that Maximillian can get in Dark Cloud 2. It's either built up from the Frozen Tuna or from the Smash Wrench. The Cubic Hammer will come with the "Durable" ability. As a weapon of the "Hammer path", it has the slow 4-hit combo, but it's quite effective against armored enemies. You can find the Cubic Hammer in dungeons' chests, you can also invent it, or you can buy it a G-Weapons in Gundorada Workshop for 950 Gilda when you get to the Chapter 5. It's a medium-tier weapon (Tier 5), which means that it'll gain 4 Synthesis Points per level-up.