Instead of having 3 identical Strengths & Weaknesses, keep it to 3 of each card, but allow the player to choose each card individually.

Example: I'm making a character who is both Highly Observant and Good With A Gun. As it stands, I can only use one of these. Under this change, I could pick 2 Highly Observant Strength Cards and 1 Good With A Gun. If I had 3 Strengths I wanted, I could take 1 card for each and pick when each Strength comes into play. Same for Weaknesses. Or, I could still make all 3 cards the same.