The GS seems to have a unique stagger compared to other weapons that roots you in place for a second before letting you move or attack. You can see this mainly on skyward slash.
This leads to a very “fun” interaction, where if you’re stunned/knocked down, and then get hit by a GS stagger, it will immediately chain into its own custom root without any time to escape, basically extending the stunlock duration for 1-2s.
Probably need a clip for this to see what you mean. My experience (and others I talk to who PVP) is that the second hit of Skyward is super easy to dodge unless stammed out.