How can you get the velocity of an offset point if the rotational velcity is stored as a matrix and not a vector?

You kind of asked two questions. To get the angular velocity vector from the matrix, decompose it into an axis angle i guess.

About the point rotational velocity:
The rotational velocity at any point is the same as the rotational velocity at the center of rotation.

Imagine a pendulum spinning all the way around. In the same time that the pendulum makes one rotation, the weight at the end also makes one rotation if viewed from the center of the weight (or from anywhere).

Sry if it was not clear, I was asking about the velocity, not angular velocity, which would be different at different points.

Altough I suppose now it does not matter as I was convinced to store the rotational velocity as a vector making the calcualtion easy to do.

Yea the linear velocity at a point is the angular vector cross the offset arm + the linear velocity

pointVel = Cross(angV, p - COM) + linV;