Change the atlatl into a launcher that throws spears. This means that Xiuhcoatl is no longer a weapon in its own right. Re-buff it by making it give fire damage to all spears thrown from it, and also reduce the weight by half of all spears in main inventory, or make them weigh 10 like daggers.
Cavemen have a lot of experience traversing tight spaces in caves, and thus are always able to squeeze through a diagonal space (except possibly in Sokoban).
Alternatively, they are able to squeeze through diagonal spaces while carrying much more weight than other roles.
Buff the axe, because its damage is fairly low for its weight, in one of two ways:
Greasing an item slightly increases its weight. If the grease wears off, it reverts to normal weight.
When riding, a lance will count for much less weight than it will normally, because your saddle is presumed to have its own stirrup for the lance. When wielding the lance, it reverts to its full weight.
Various types of floor traps trigger based on your weight. This makes the trap more likely to trigger on a heavily armored character or one who has collected a lot of loot. Would work nicely in the Gnomish Mines, since gnomes are light and don’t tend to carry much stuff. Certain traps could also trigger to a lesser degree if you weigh enough to trigger it but not a whole ton.
Any item can be dipped into a potion of levitation to permanently reduce its weight by 20%. This uses up the potion, and it will only affect the item’s base weight, not the weight of any contents (i.e. a bag of holding thus dipped will weigh 12 + contents instead of 15 + contents). If the object is canceled at a later point, it loses this property and reverts to its normal weight.
The effect cannot be stacked; attempting to dip an already-levitated object into another levitation potion will have no effect and will not use up the potion.
A possible variation is to also confer this effect for potions of enlightenment, since “enlightening” the item could be interpreted as making it physically lighter.
Bags of holding give a flat reduction in weight (proposed amount is 150 aum) and only apply their usual halving or quartering to any weight in excess of that. This makes it beneficial to find and carry multiple bags of holding.
Blessed loadstones boost your carrying capacity by more than their weight, allowing you to carry more than if you were not carrying the stone at all. The stone would probably still curse itself upon leaving inventory, however.
If you fall downstairs while fumbling, you may land on a monster that was already occupying the upstairs of the level below, damaging them proportional to the weight of your armor and possibly reducing the damage you took from falling down the stairs.
Armor and weapons are heavier when they are cursed than their normal weight.
For giant player characters, huge chunks of meat should weigh the same as boulders (i.e. light enough to pick them up easily).
Loadstones operate more subtly: they increase their weight every time you pick up a new item (one that you haven’t touched yet in the game). At some weight threshold, it autocurses and becomes undroppable.
Carrying a loadstone makes all stone-type missiles (slung ammo, etc) deal double damage - increasing the payload of stones. Also, when blessed or uncursed, it doesn’t weigh as much as cursed.
Within Sokoban, boulders weigh 6000 for giants, just like anyone else, so you can’t carry them around.
Make potions lighter, on the order of 5-10 aum, on the basis that potions are one-time use and one-time use objects shouldn’t be heavier than many pieces of armor, and also on the realism basis that at their current weight, they’re a few liters of liquid. The counterargument is that if potions are lightweight, there’s less to prevent the hero from scooping up everything in the dungeon as they go.
A tinning kit’s weight is dependent on how many charges it has left, getting lighter as it is used to tin things. This could also be extended to other tools which have charges and are not magical, such as cans of grease.
Polypiling can’t create matter out of nothing. If an item is trying to polymorph into a heavier item, it must absorb the mass from other objects in the pile, destroying them. Note that if polypiling a stack of same-weight objects (potions, or scrolls), none of the candidate items will be heavier, so this will never trigger.
Spell staves are made into poor melee weapons (comparable or worse than the club, being basically a stick that’s just sturdy enough not to break), but are made lighter than the quarterstaff, weighing only 10. Its bonus to a single spellcasting school is countered by it applying a slight spellcasting penalty to spells of some or all other schools.
Monsters, including the player, under a certain body weight plus inventory weight don’t trigger squeaky boards. This weight factor is fairly light, possibly in the low hundreds (so even a player carrying nothing will still trigger it).
You don’t take damage when tossing lightweight, non-hard, non-weapon objects upward. “Light” is defined by some weight threshold. (It’s very weird that you can take damage by tossing, for instance, a eucalyptus leaf in the air.)
Alter the player’s corpse weight based on how hungry they were when they died.
The potion of levitation has negative weight, and lightens your inventory load rather than weighing it down more.
The weight of your character varies depending on your hunger status.
Float stone, a gray stone which has negative weight. Non-stacking, and rare. If you get enough float stones to more than cancel out your own weight and the weight of any possessions you’re carrying, you levitate. Possibly doesn’t work when put into containers, or at least doesn’t get multiplied by the effect of a cursed bag of holding. May gain positive weight when cursed, or greater negative weight when blessed (or vice versa).
More harassment effects: the chance of respawning the Wizard is a fixed 1/7 and the rest of the effects are equal probability. Multiple non-duplicate effects may happen at the same time.
