Question on how speed works
 

I noticed that there is a certain stat that makes items slow you down less.
Is it strength?If so, by how much is it worth making stuff weigh you down less by investing 1 or 2 points into strength?Would it be a big change in speed?

With 27 Str I can carry up to 450 kg without being slowed down.

Strength affects the amount of maximum weight you can carry. The more weight you carry the more it will slow you down. The more strength you have, the more you can carry without being slowed down. Rings with strength add 250 maximum weight per str, while body armor adds 500 maximum weight per str, so if your ring grants 4 strength it will add 1000 maximum weight. Other items affect how much maximum weight they can give.

Almost every armour will effect speed even if you have high strength the only body armours you can use without your speed going down are Gale Armour and Plate Mail of Power also Mith but only if you have less than 26 dex.

I thought it was 250kg per 1 str up to 29>30 str which adds 500kg :o

each lvl between 20-25 gives you +150kg max weight
each lvl between 25-29 gives you +250kg max weight
the last 29-30 gives you +500 kg max weight.

If i remember correctly 4500 kg is max. at 29 str i have 4000 max.

If I had debug I would test out 10-20 if possible.

That seems correct.

Doesent STR also increase your dmg?
What does?(Other than weps themself)

str also increases WC(Weapon Class). when you increase wc the number actually gets lower. somtimes 1 str doesn't add weapon class. depends on what level you go to.