Just finished the game and Mend also have a similar issue - you can get away with way less health on the mage and never realise Mend is an option. I ended finding it at the very end, when I ran out of every other upgrade vs the final boss, so I had to get mor health on the mage.
Just as a potential idea - it might be useful to show if there are branches coming out of a specific idea. This way even if you don't need it you will see that it might unlocking something that you might need!