Wyverns attack with melee, ranged or their unique ice-breath attack. This attack can freeze players, and they will be stunned as well, so escaping is not possible unless Freedom is used to break free (this is currently glitched and will not free the player like it otherwise should, although it does break the stun).
If a player is not wearing one of the shields they will be hit for very high damage. Contrary to popular belief, armour does not affect the accuracy of the ice-breath attack, the ice-breath will hit regardless of armour.
Wyverns will use a ranged attack both when players are attacking from a distance and when they are attacking within melee range. Their melee attacks are comprised of a bite and use of the tail.
All my long hours of research have finally paid off! Today I discovered an ancient journal in the great library, which detailed a ceremony for giving life back to greater beasts after they have died! I shall finally be able to unravel the secrets of the Skeletal Wyverns!