Why does Buckbeak's executioner use an axe? [duplicate]

Question

I've only just identified something which has been bugging me for literally years.

Why does the executioner Fudge brings to kill Buckbeak use an axe?

Seriously, one Avada Kedavra and it's done with zero pain, zero mess and zero effort.

Possible arguments and why I think they're wrong.

• Not every wizard knows how to use the killing curse. - Sure, that's true but we know the Ministry of Magic employs aurors, and employs someone purely to execute dangerous animals. So that wouldn't be a problem.
• It's an unforgivable curse, it's illegal. - The fake Professor Moody makes it clear that the unforgivable curses are only illegal when used against a fellow human being, then uses them on spiders by way of demonstration.

Here are some possible real-world, fiction writing, reasons (I'm not looking for these):

• The image of an executioner with an axe is a frightening and dramatic image.
• The sound of the axe coming down gives the kids a reason to falsely think Buckbeak has already been killed.
• This might make it easier for Harry and Hermione to escape with Buckbeak.

So, are there any in-world reasons the ministry would choose to use an axe instead of a spell?

Answer 1

It may actually be the surest and easiest option

1. To paraphrase Buffy, very few things can survive without a head. In a world like HP canon where many magical creatures (e.g. giants, dragons) are resistant to curses, death by beheading would likely be a "surer" option.

2. Another possible reason: it is suggested that the unforgivable curses have an emotional component: In OotP Bellatrix says:

   'Never used an Unforgivable Curse before, have you boy? ... You need to mean them ... You need to really want to cause pain'

   if this is widely known, the ministry would probably not want to employ people who 'really want to cause death' or at least not advertise that they do so by letting employees openly cast the AK.

3. The fake Moody indicates in GoF that the AK needs both intent and power, stating that the entire class could cast it on him at the same time and it probably wouldn't even give him a nose bleed. Which means the AK may not be that easy. So using the axe is probably less difficult / less tiring than the AK. Someone who has to kill things frequently for a living might not want to waste the energy, and if they were just a mediocre wizard/witch might be unable to cast the curse at all.

4. While not well defined, it is suggested that "dark" magic has a corrupting influence on the caster, so many wizards would just avoid casting unforgivables on principle, or for appearances' sake - to not have others think of them as "dark".