I’m quite possibly the only person in the world this bothers, and me only in passing, but it’s always seemed weird to me the way carrying capacity works in d20 games, and particularly the way it interacts with combat.
It’s probably reasonable to assume I’m the average Str 10 NPC, which means I’m unencumbered when carrying a toddler (33lb.), slightly slower (but still able to run!) when carrying two toddlers, and still slightly dextrous and moving pretty rapidly when carrying three toddlers. Well, okay. Dramatic licence and all that, plus you want chracters to be able to transport significant amounts of stuff (including fallen comrades and massive piles of gold), so damping down the effects of heavy stuff seems okay.
However, the rules also allow me to fight at full effectiveness when carrying three toddlers. That’s right. I may be slow, unstealthy, and off-balance, but I can duck, weave, thrust, parry, spin and hack as much as I like regardless of how much I have strapped to my back. This isn’t just a question of weight, but one of balance. I very much doubt my camping rucksack approaches 100lb (internet suggests an army pack is around 50-70lb), but the idea of fighting in it is ludicrous – even turning around quickly is difficult. Soldiers use special packs with quick release straps to drop them if a fight breaks out, but it’s never implied that adventurers do anything similar. Adventurers typically cart all kinds of potentially fragile materials around, but their luggage never gets damaged in combat, as you’d expect if they’re brawling with bears. Blades and maws don’t seem to rip canvas and spill contents, missed attacks never stab into packs and stick, or shatter potions.
So, what if (hypothetically) we wanted things to be more realistic here? My suggestion would be to have encumbrance – but not armour, which is already dealt with by armour proficiencies and feats – apply its check penalty to attack rolls and to AC. It’s simple enough. The same applies to large and bulky items that would cause significant inconvenience, regardless of their weight - ever try carrying a big pile of styrofoam?
Adventurers of increasing level will find the penalty much less of a problem, which reasonably reflects increasing familiarity with fighting encumbered. Those wanting to avoid the penalty need to adopt tactics other than simply strapping everything to their backs: using pack animals, leaving non-essential gear outside when exploring, or dropping packs when they expect trouble. These are all realistic solutions to the issue.
Dropping a pack should realistically require a move action (medium encumbrance) or a standard action (heavy encumbrance). This is potentially risky if you’re carrying fragile items or fighting in awkward environments. Stowing a pack (or carried object) with extra care, so it won’t drop into an acid pool or off a walkway, may require an additional action.
For anyone worried by the penalty, there’s a simple option of offering feats:
Encumbered Proficiency (Medium) [General]
Benefit: You treat your encumbrance as one step lighter for the purposes of determining attack and Armour Class penalties.
Encumbered Proficiency (Heavy) [General]
Benefit: You treat your encumbrance as two steps lighter for the purposes of determining attack and Armour Class penalties.
Battle Porter [General]
Benefit: You can drop a pack as a swift action, or carefully stow a pack as a move action.
Normal: Dropping a medium load requires a move action, and dropping a heavy load requires a standard action. Stowing a pack carefully requires an additional move action.
This approach might encourage players to think more carefully about what they would realistically tend to carry on their person in pouches and pockets (thieves’ kit), what would be in an adventuring pack they take with them (50’ of rope), and what might be brought along on journeys but typically left at campsites unless they expect to need it (portable forge, 500 arrows). Most of the time this won’t be an issue – they can nip back to collect bulky items if they’re needed – but occasionally it will limit their options, hopefully in interesting ways.
So yeah, just an idle thought I felt like fleshing out, really.