How does weight penalty work?

[Macropus]

It's a bit hard to explaing what I'm asking about, but I'll try my best.
In which way does it work?
1) My gear weight (20) decreases my movements by amount equial of 2 athletics point, so if I have base 9 athletics, my "effective athletics" would be 7.
2) My gear weight (20) decreases my movements by 30%, so if I have base 9 athletics, my "effective athletics" would be 6.

Obviously enough, if it works in 2nd way there's no sense to use heavy armor for high-agi characters, so what I'm asking is basically "Is there a sense in using middle/heavy armor with high athletics character, or would athletics become nearly useless due to the armor weight?".
Thanks in advance.

[rustyspoon]

Weight increases decrease running speed by a certain percentage. If the math I found on this warband wiki is correct: http://strategywiki.org/wiki/Mount%26Blade/Skills#Analysis

each point of weight will decrease your movement speed by .44%. So, 20 weight would reduce it by almost 9%. 1 point of athletics is equivalent to 4.16 less encumbrance or a 1.83% increase in running speed.

As 4 agi is worth roughly 1 point of athletics, rounding up would give you a total athletics skill of 16. 16 * 1.83 would increase your base running speed by 13.28%

Your 20 weight would decrease your running speed by 8.8 percent...a pretty big reduction.

The unfortunate thing in this game is that weight penalties are percentage-based. That means that builds with higher athletics get hit harder by weight penalties than builds with less athletics. If you're doing a heavy athletics build, it's really a waste to use anything but light armor.

[Macropus]

Thank you so much for that info!