This is very good actually, what I would like to know however is what do you think of allowing all the people who are medic and did not chose taijutsu to have an advanced mastery from this idea.
For instance as you said in the topic a lot of people go Water+Medic which will result in them never being able to get a fusion, but what if you allow them to be able to chose Advanced Medical(INT). They would have a weaker version due to splitting of stats but they won't be left behind in the update. This is more for the majority of people who are Medic + Water/Wind/Fire/Earth/Lightning/Weapons.
That being said Medic+Weapons definitely sounds like Hanzou to me, where one can learn to coat their blade in poison (Which silences on impact) have a better version of poison fog and finally a new application of poison where the poison gets stronger the more a person runs to a cap. All just an idea thank you for reading.