cast on crit bug

I have been able to reactivate my "Cast on Crit" ability on weapon set 01 by doing the following:

Thank you to all who have shared the tip here. It has been really helpful :-)

Below, a short explanation in picture mode :






Drawing arrows is not my master skill lol; I'd rather prefer to fire them in-game, the place where my skill is shining with arrows. :-)

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@GGG & Hello : The "missing" terminology for the wording is confusing.

I would rather prefer this wording; it would have enlightened my neurons early for a solution:

The 'Cast on Crit' gem can't be activated because the required skill 'Skill Name' has not been activated on this weapon set.