[vicky_molokh]

Something I've been thinking of more for characterisation than for efficiency. Specifically, if you happen to have Brawling instead of Judo/Karate, you might consider showing brutishness by biting the enemy. Note: approach is made more for RP reasons than for safety; do not try this at home.

I'm working on the assumption that you have Brawling 18 instead of Judo 16 (due to cheaper skill) as per OP, while the opponent has Knife 12 (I haven't seen enemy skill level specified).

RAW Variant 1 (the basic).
Declare a Wait.
When opponent steps into attack range, your Wait is triggered. If you need to, step forward. Now bite you're opponent's knife arm (-2). Do not let go. Taking -2 or even -4 Deceptive Attack for a -1 or -2 to defence is reasonable, more if you're desperate enough to do an AoA (Determined). Knife-12 grants a base Parry 8.
If you're successful and the enemy failed to Parry, you're now grappling his knife hand, so he can't use it - he has to break free, which he has a 45% chance assuming equal ST (bite counts as one-handed grapple). Next turn, if he didn't break free, you can add two hands to your bite-grapple, for a net +7 to your ST in the break free resistance, and proceed to making Knee Strikes to his groin for a mere -1 to skill, against which he defends at -2.
If he Parries, he can opt to hit your face with the knife (if he makes a successful Knife roll), which is bad, but the risk seems worth it. If he decides to strike you instead of breaking free, he's at -4 DX.

RAW Variant 2 (the tricky).
Declare a Wait as above, but use a Stop Hit (not Stop Thrust!) instead.
You're very likely to win the Quick Contest, providing the enemy with -3 on on his Knife Parry from that alone. You probably shouldn't lower your skill to less than 14, whether you AoA or not.

Note that if you're using unofficial Step-while-already-Waiting that allows the knife-wielding attacker to arbitrarily trigger a Cascading Wait, you're (a) essentially forced into something close to Variant 2, so you probably want to use Variant 2 anyway and (b) you're still very likely to win the QC.