You've mixed up your priorities; Adept (Magic 6, Skill 4) is B. If you swap A & D, you could hit your edge cap, or you could swap A & B to get a few more attribute points.
Attribute Boost: Strength will increase your strength, but specifically only applies to dice pools. Unless you plan on entering any strongman competitions to lift cars, or need the running speed, it's not that useful.
As for how to further your mastery of knives - throwing.