So, let me let you in on a little secret. I don't like encumbrance rules. I've never liked them, and I don't think I ever will. I mean, I get it, you can only carry a certain amount of weight at certain levels of strength. I have nothing against that idea. It is the implementation that always seems to get at me, especially when it stops a character from being able to carry basic gear. Yet, it is a common system, and method, for keeping players from just loading themselves up like some console RPG character with a bottomless sack of stuff. Still, I think that there has to be a better way.
So, just to get it out of the way right at the beginning, my key problem with encumbrance is how arbitrary it is. You have a strength of 12, and can therefor only carry 30 lbs of stuff without being slowed down. Not a problem in and of itself, but then you find that basic armor weighs 25 lbs, and a basic sword weighs 7, and a shield weighs another 10. You haven't even put a backpack on, and your slightly above average strength character can't move because of how much stuff weighs.
Heck, he can barely even lift his sword if he can only carry a total of 30 lbs and the sword weighs nearly 7 of that. The sword alone is nearly 1/4 of the total weight he can carry.
Now, granted, this is an exaggeration, but it is not that far off from one. The problem is the arbitrary number doesn't account for the basic fact that when you spread the weight around, it is easier to move in it. In other words, you're going to feel a 30 lb backpack's weight a lot more than you'll feel 30 lbs of clothing. Yes, they're both 30 lbs, but one is a lot more manageable.
This probably sounds like whining, and in a sense it is. If I've made one thing clear on this blog, I hope it is that as a player, I don't think you should ever be told that you can't do something. Now, the answer here could be simple "you want to carry that stuff, than raise your strength. It is how the system is balanced", and I could argue that there should be viable alternatives for lower strength. Then we can go back and forth about who is right and wrong, but the base fact is that I have a few assumptions that I think some game systems just don't take into account. They are, as follows:
1) An average strength character should not feel like they are weak, except in comparison to an above-average strength character.
2) Average is dependent on the population the character is from. In other words, your argument against average strength limiting me shouldn't boil down to "All fighters have above average strength"
3) A character should, unless they have specifically made strength a weakness (see #1) be able to wear some basic form of armor and wield a basic sort of weapon without penalties.
#3 there is the big one. Essentially, arming my character - who is not weak - should not make it impossible for me to carry basic provisions without having to move at 1/4 speed.
So, what do I suggest in exchange? Honestly, common sense. If a character is weak (below average) they should not be able to carry as much as an average strength character, who in turn should not be able to carry as much as a strong character. Aside from that though, use common sense. There is only so much room on the body where it can still move comfortably, so use that.
if something is reasonable to be carried, let the PC carry it. If they are getting to the point where you think they are heavily pushing the bounds of their strength, then let them know. The 'Carry Weight' a system will give you is a great guide, but a horrible absolute to use. This can actually be true with a lot of physical endeavors.
The main point is though, that games use abstracts to manage so much. We have a number that represents an approximation of our strength, our charisma, our agility, our speed. Why is it suddenly harsh math when you want to carry things?
To point that out a bit clearer. Lets look at that example above again, the fighter with average strength who is encumbered because he has on 42 lbs of gear between his armor, sword, and shield. 12 lbs over weight with those three things. Now, according to the system, that same fighter could carry 30 1 lb blankets with no hindrance to his ability whatsoever. Have you ever tried running around holding onto, or otherwise carrying one blanket? Let alone 5, 10, or as many as 30. It just doesn't make sense.
Granted, that is a silly example, but it is still an example. A weight based system doesn't take account, at least not fully, of what is likely to really slow you down when moving, which is the size of the object. Which, awesomely enough, is where I would recommend making the change to systems for carrying things. For example, lets look at video games.
For First Person Shooters, there was a change made to inventory systems that became very popular with Halo. Namely, the main character only had so many weapon slots. Now, Master Chief is a very strong person in power armor. He can rip a mounted gun off of its tripod, and run around shooting it when he needs to. However, he can only carry 2 (max of 3 when holding that big supposed to be mounted gun) weapons. He just doesn't have the room for more weapons, and so can't carry them.
For RPGs, perhaps looking to other RPGs is better. Give characters slots to carry things on. A clothing slot, gloves, boots, armor, main hand, off hand, back, head, etc. This limits the amount of stuff that the character can have ready at any given moment, and you can easily use common sense for this. For example, someone with a 6' spear worn at their hip is going to have more issues moving than someone with a knife at their hip. Everything else goes into the backpack. It is then out of the way, harder to get to, and all in one place (or several if you allow multiple packs). Then, if you feel the need for it, you apply the encumbrance rules to that backpack. Afterall, a 40+ pound backpack is going to be felt a lot more than that stuff worn all over the body.
Course, if you like how encumbrance works than you're golden. For everyone else, we can find other - potentially better - ways. We just have to look.