Hey, awesome mod by the way!
Wanted to point out that i feel that the mystic sword item is extremely powerful for a green item.
It can easily give you a huge boost to damage very quickly, maybe too quickly as it stands. Me and a friend have been finding ourselves dumping every single green item we get into a printer to get more whenever the opportunity comes along as it pays for itself in damage in only a couple minutes. 

I think the item either should be made a red item and have a slight buff ( 10% +5%?) or be nerfed/changed from its current 3% +3% to something like a 5% +1%.  Would encourage you to have at least one but not effectively make your entire build just stacking as many as you can.

If you are just doing the one loop straight to the boss then it might be fine where it is, but if you are doing more then one loop then it sky rockets in strength.

Even without looping this item has high potential if you get one on stage 3. It can be farmed on Combat Shrines or on any shrine with Defiant Gouge. Maybe make it have diminishing returns on enemies that don't qualify as a boss or simply move it to a red item and bump up the stats a bit.