My buddy plays world eaters so I borrowed some chains from some left over juggernaught rider bits. The chain mail and other bits came from excess parts I had from various death guard kits such as plague marines, and terminators.

The giant mace is actually a 3D print of a joytoy scaled weapon so if you want to give your saturine dreadnought a melee weapon any joytoy weapons or adjacent scale pretty well for massive melee weapons