Control Law singularity when equilibrium is reached

Question

I am working on a control law that has the form $T = \frac{K (\vec{a}\times \vec{b})}{|(\vec{a}\times \vec{b})|}$ that tends to make the cross product $\vec{a}\times\vec{b}$ equal to zero by aligning vectors $\vec{a}$ with $-\vec{b}$. I have proven that, assuming $|\vec{a}\times\vec{b}|\neq 0$, the control law is asymptotically stable by Lyapunov technique. However, I cannot fully understand the fact that the system tends to an equilibrium that causes a singularity in the control law.