In marmoset toolbag 1.0, ambient occlusion was based off of your model's size, so if the scale for your model was off (1 CM compared to 1 M for instance) the AO might look too heavy or too light. For PBR, I highly recommend having an occlusion map plugged into your material, also.
Hi, great job on your first PBR model! If you're still open to critiques and changes on this model I would suggest changing color of the gold/brass parts to be a little bit more "goldish" than just a toy yellow tone. Metal itself is kinda OK but I think it lacks the depth, also the blade seems a little bit too grainy for a…