the key to understanding how to use the Axe, is in what
SorO_Lost posted .....
using a Headsman’s Axe ... is a Skill check, it is not an attack roll, but the check can be made in the middle of combat Provided you meet the the Execution Requirements
Headsman’s Axe: When specially sharpened and held with the proper technique, a greataxe (or a greatsword) can serve the executioner as the instrument of execution. The condemned is restrained, with the neck vulnerable to the strike readied by the executioner. On a successful Profession (executioner) check, the condemned dies instantly. If the executioner fails the attempt, the headsman’s axe delivers a coup de grace against the condemned (automatic critical hit, and the condemned must succeed on a Fortitude save or die). The coup de grace simply completes the executioner’s task more messily.
"the proper technique" refers to a Skilled use of an
"instrument" which in this case happens to be an Axe
to understand more clearly ....look at the rules regarding Execution:
RULES OF EXECUTION
The condemned must first be secured by being tied in place, pinned in a grapple, or successfully restrained in a stationary execution device. If restrained in an execution device, the condemned can attempt to make a Escape Artist check every round against the DC noted in Table 3–2, unless magically held or otherwise helpless. If grappled, the condemned can attempt to break the grapple normally.
Once the victim is secure, the executioner can attempt the chosen method of execution. The executioner makes a Profession (executioner) check against the DC given for the device on Table 3–2. If the check is successful, the condemned is slain according to the nature of the device. If the executioner fails, the execution is botched, and the executioner can make another check the following round. Botched attempts deal the damage noted for the device, so the condemned may be killed even if the executioner botches the attempt. Prideful executioners—which includes most of them—take it as a personal point of dishonor if they kill the condemned on a botched execution.
Execution Devices as Weapons: Some execution devices, such as headsman’s axes, make adequate melee weapons. In melee, such an item deals normal damage for an item of its kind (such as a greataxe) and cannot kill instantly. Most other devices of execution cannot be used in melee.
Masterwork Devices: Masterwork execution devices provide a +1 circumstance bonus on the executioner’s Profession (executioner) check. They cost twice as much as the versions given in Table 3–2.
in most Combat situations it is not possible for a single character to do both :
1) Pin the Character and
2) be free to make the Profession(Executioner) skill check, since it also requires a readied action to make the check
the Axe is not being used to make a Combat Strike but a precise swing at a helpless target .... also the weilder is not in Combat per-say, rather
the assistant who Grapples and Pins the Victim is in Combat,since Grappling is a Special Attack Action. The weilder of the Axe simply waits until the victim is
helpless, then practices his Skill at Execution
if used as a Melee weapon, it simply does damage as per a regular axe of its type(modified by any enchantments it might have) .... it has no ability to Insta-Kill. Executions are not combat situations and are governed by different rules.