Finisher damage in this case is the combo jab move of the weapon
The Stun Baton is a default backup weapon for enemies that are Disarmed by certain abilities. It is used by both Grineer and Corpus enemies alike, but only used by enemies who are not already melee-focused enemies such as Butchers.
Regardless of the enemy which wields the weapon, it will deal a base 60 damage in the hands of a level 1 enemy, with each level adding approximately 3.2 additional damage. Therefore, it can be assumed that a level 100 enemy will deal about 380 damage to shielding with each swing.
Additionally, combo "Jab" moves can be done by enemies which will inflict about double damage, which would equal 120 at base level or 960 at level 100. Note that these numbers are based on tests conducted on shields on level 1, 6, and 11 enemies, and was not tested on health, due to the damage type of the weapon not being known.
All units use the same model of the Stun Baton regardless of their size, resulting in the Stun Baton looking disproportionately small when wielded by large enemies such as Bombards or Techs.
All MOA variants (including Mutalist MOA), when disarmed, will have this weapon placed on top of their gun, akin to an antenna. They will not use this weapon however, and will simply resort to kicking players instead.
All Osprey variants can also be disarmed, having all their abilities stripped and will be forced to the ground. If the Osprey has a weapon, it will have a Stun Baton sticking out similar to a MOA.
The weapon deals the same damage regardless of the faction it is wielded by.