It's made relatively clear in the movie as there is nothing happening to suggest that any stones are being used when he's fighting Hulk.
As far as Thor needing his weapon to defeat Thanos, think that was just on account of Thanos being so much more powerful than anything he's fought before. But I dunno, might just go to the fact that both movies were probably in production at around the same time and being made by different groups of people, so there might just be some inconsistencies.