You can label things hard/soft or internal/external but any close examination of what those labels are attempting to mean in the real world leads immediately to basically "nobody agrees on a definition and anything can be labeled whatever fits your theory."
Definitely 'real' world kind of makes hard and soft (yin/yang) at minimum pretty bad because a martial art which had solely one or the other wouldn't be functional aka "Philosophically Imbalanced". (hence my designating them as the difference between weapon attack and armor defense techniques and a Martial Art would generally include both.
However - Note a weapon technique have the
Defensive property - (which may be the property I replace things like
light thrown with (for the knife hand technique) or some weapons which are currently
heavy thrown might become
Versatile instead.... ie the weapons arent necessarily going to be identical analogs. A versatile technique represents techniques which work well in a kick or punch fashion ie 1 or two handed), a snap kick is analogous to a one handed kick though so even a versatil or one handed art could be visualized as all kicks. The idea is to be descriptive rather than prescriptive ... The Shotokan Karate style uses very few kicks prefering to emphasize lunge punches and similar though I personally loved snap kicks. A TKD like art would emphasized kicks (ie 2 handed or mayhaps versatile)
Obviously you can do better than that in a game, since you can pretty much decree what is what.
True though my martial arts nerd may kind of enjoy that bit of quasi realism in my model too. But since it doesn't follow the myth perfectly It might be biting my own hand.
So, maybe 'internal' is a technique that benefits you, and external is one that disadvantages an opponent. Hard deals in damage modifications, soft deals in defenses. Of course it will be tricky even there to define the difference between a 'hard internal' technique and a 'soft internal' technique in most cases.
A Advanced Defensive Technique emulating Crysteel Armor -- grants bonuses to Will for instance.
I can do some arbitrary labelling in the descriptions too so calling things Internal and External for instnce but unless they interact as a proficiency or with feats or something it doesnt really matter too much
this is about flavor anyway I think
Speaking of Yin and Yang - Yin is said to hold in its core Yang and vice versi... some of these techniques will demonstrate that.
An Armoring Technique using Strength is kind of a Soft Technique with a Hard core...as one is probably interfering with attacks as part of ones basic methodology. But the explicit Blocking Techniques or Striking Techniques (with defensive property) are even more so ... sure they are defensive but in an aggressive fashion or aggressive with a defensive element.
