Blending doesn't work too well with vertex animations, you can only blend between two full (integer) frames.
Imagine the following scenario:
"walk" consists of 10 frames, my.skill2 is 37. After the instruction
ent_animate(me,"walk",my.skill2,0);
your model's mesh will be blended by 70% from walk frame 3 to frame 4.

When you now call
ent_blendframe(me,NULL,"stand",6,75);
you try to blend the walk frame 3.7 and the stand frame 0.6 but as you can only blend between integers resp. the "entity.frame" and "entity.next_frame" parameters, the result will be a blend of walk frame 4 (or 3, I don't know if the function searches the closest or the next-lower integer) and stand frame 1 (or 0). Thus there will be some kind of snapping.

It's very hard to explain, especially in English, just keep in mind that ent_animate and ent_blendframe (probably) only set the frame and next_frame parameters, the resulting mesh is calculated afterwards before rendering.


EDIT: What you can try is to let an animation reach a full integer frame and then blend to another integer frame of the stand cycle.