Your attack speed is average

[starless]

A centaur wielding a hand crossbow and Crossbows at 11.0:
"Your attack speed is average (and cannot be increased with skill)."

How come?

[tasonir]

Average means it's at 1.0 turns, as vague a notion as turns are, or 10 aut. While most weapons (anything but crossbows and the dark maul) have min delay that is less than 10 aut, crossbows stop at 10. So you're at min delay, and get the message about skill no longer helping. If I recall, min delay for a hand crossbow is 10 skill.

[Lasty]

Min delay for all crossbows is 1.0.