To get powerful weapons early on in the game, do the following.
After you find Vulgrim for the first time, go to the weeping crag dungeon and climb to the top to get a key. And there should be chest up there. Save before opening it. Once saved, open the chest. If it's a crap weapon or armour, then reload the game by quitting. Just keep reloading the save until you get what you want.
Another method is, when you have at least 40 boatman coins and a lot of Gilt, go to Vulgrim and buy the purple box. And occasionally, the orange box. But once again, save before buying anything. The purple box gives you elite weapons/armour while the orange box give you possessed weapons. But the orange box is extremely risky and most of the time gives out nothing.