Average skill in duel report:
The day before my last duel the skills with spear and shield were 97%.
The duel report also said 97% (average skill).
So I guess the daily decrease is scored after the duel.
I think
2/3 x forehand skill ( 75% ) + 1/3 x offhand skill ( 30% ) = 60%
should be right.

Daily skill decrease:
As far as I know the skill doesn´t decrease below 45% when it at one time was higher than 45%.
When the skill is 100% the decrease is 2 points as far as I know.
Looking at Jjahs table I guess it should be:
From 30 to 45 skill points = skill +-0
From 46 to 74 skill points = skill -1
75 skill points = skill -?
From 76 to 100 skill points = skill -2

Skill increase because of duel:
There I´m not sure, how it works.



Jessica vom Greifenstein wrote:

QUOTE:

But I remember Alrik having skill with kind of weapons he never used (but don't know which it was, if I remember right it have been the blade weapons... which he never used always having slash weapon).

This should be a bug that happens sometimes during a tourney:
http://ritterheere.de/component/option,com_fireboard/Itemid,181/func,view/id,409076/catid,2/