Longbowmen's stakes in sieges...

[Ice]

It seems reasonable. It makes sense defenders woud block the only entrance into the city with sharpened wooden stakes.

[Zatoichi]

Yes, but as there's only a very small minority of factions which can do it, it makes for a somewhat unbalanced advantage when defending in sieges.

On top of this, it's not a tactic the AI ever employs, suggesting even more that it is an unintentional bonus for the human player.

The trouble is, cheesy tactic or not, it's so darn tempting!