In edit mode, move all the vertices of the sword until grip is in the origin of the scene, then exit object mode. Shift+C - Centers the cursor at the origin of the scene. Ctrl+Alt+Shift+C - Opens a menu related to the origin of the object, select "Origin to 3D cursor" (which is at 0,0,0) This way you have the object's origin in the correct place, and the object is ready to be exported since it's already centered.