EW was originally made to match the fight scene between Wesley and Inigo Montoya in the Princess Bride it is a great scene, and the entire "I know this style, therefore your style is insufficient", "Ah, but I know this to counteract it" banter is definitly a thing to use in 7th Sea.
However as the number of schools exploded, the use of a single specific EW became less and less. the swordsman guild book tried to make that somewhat less so, but it still didn't work.
However dropping EW isn't attractive either because it takes away the trope of the "secret school" that noone can really defend against.
So I'm dividing EW into two parts the EW (SS) knacks and knowledge of a school.
Exploit Weakness (Swordsman School)
This knack is now a measure of your ability to use the advantages of a school against the disadvantages of another. thus the knack gives a bonus of unkept dice to all rolls against a swordsman using a school you have Knowledge of, while you are using the school the knacks is bassed in. it also reduces the EW of the opponent who is using a school you have Knowledge of.
I.e. two characters with similar styles, equal EW in the styles they are using, and both having Knowledge of the others style, will have no advantage against each other. (this is simply to reduce the number of dice rolled, and to represent that a master is also better at covering up the flaws of his style than a apprentice).
(I'm considering renaming the knack Mastery, it sounds better, and implies a more general facility with the advantages of the style)
Knowledge (Swordsman School)
Having Knowledge of a school allows you to use your EW (SS) against him. Knowledge is binary (so far), either you have it or you don't.
to gain Knowledge of a school you need to gather five "ticks" in it. There are two ways of gathering "ticks":
1) Fight a user of the school in a serious fight gives one tick.
2) Spending a day studying the style (training manuals, sparring, or just hanging around the school observing the students), allows you to spend one XP to gain one tick. (The XP cost is to prohibit a swordsman from going crazy in a month of downtime and having mastered all schools in the area.)
Individuals with no school have their own style giving Knowledge (Opponent). If they later learn a style, you need to get to know that style.
Grandmastery combinations are their own Knowledge, however you start with two ticks if you know one of the styles in the combination, three if you know two.
Is the above even intelligeble for anyone else than me?