The Masher is a unique weapon in Super Mario RPG that you can collect for your party. It is a useful weapon and way better than your basic Hammer and Super Hammer because of its high attack damage.
After getting the Third Star piece, you will need to make your way to the Booster Tower to find it. Below, I have covered the complete details about the location of the Masher weapon.
Super Mario RPG Masher Weapon location
You will find this weapon in Booster Tower that you will find in the Moleville Region.
After you enter the Booster Tower, you can explore the area. This way, you will come across a room where you will observe a seesaw, and on the other side of that seesaw will be a Bo-bomb in Super Mario RPG.
You can leave it and then proceed back to the main entrance and then head right towards the floating steps. Jump on each of these steps to reach the upper area, and after you cross six portraits, you can enter through the passageway on the left end.
You can continue onwards and jump on the steps and then cross a giant yellow and blue cube pillar in Super Mario RPG. Turn right after you get across it, follow the steps, and take the first left turn. The passage will end a short way, and if you look above, you will observe a treasure chest levitating above you. You can try to jump and hit it, but you won’t be able to do that right off the bat.
You can go to the edge of the passage and jump down on the seesaw you came across earlier in the initial room of the Booster Tower. Once you land successfully on one side of the plank, the Bo-bomb on the other side will be thrusted towards the chest above you. This way, you will collide with the chest and get the Masher in Super Mario RPG Remake.