After reviewing the discussion and the various house-rules linked above, I think I am going to test the following in my next game(s).
UPDATED RULES
Encumbrance and Thievery: Thieves benefit from being light on their feet. If the character’s encumbrance is 5 stones or less, he gains a +2 bonus on throws to hide in shadows and move silently. If the character’s encumbrance is 2 stones or less, the bonus is increased to +4. The bonuses do not apply to hijinks.
Open Locks: Each attempt to pick a lock requires 10 minutes. A thief may try again if he fails to pick a lock. However, if a thief rolls a natural 1 while attempting to pick a lock, he has broken his thieves’ tools.
Remove Traps: Each attempt to disarm a trap requires 10 minutes. A thief may try again if he fails to disarm a trap. However, if a thief rolls a natural 1 while attempting to disarm a trap, he has set off the trap.
NEW EQUIPMENT:
Armor oil: Lubricating oil which quiets the creaking and squeaking of leather armor. The encumbrance of oiled armor can be ignored when moving silently for the purposes of the encumbrance and thievery rules. A pint of armor oil will keep a suit of armor oiled for one week. Cost: 2gp.
Cloak, camouflage: A cloak woven with a colored pattern that makes its wearer harder to see. Camouflaged cloaks are available in a variety of colors and patterns for various environments. If the cloak’s camouflage is appropriate to the environment, the cloak adds a +2 bonus to any proficiency throws to hide in shadows, avoid being spotted, and evade in the wilderness. Characters wearing appropriate camouflage cloaks can always hide in shadows or avoid being spotted with a throw of at least 18+. It imposes a -2 penalty if the camouflage is inappropriate to the environment. The bonus and penalty do not apply to hijinks. Cost: 15gp.
Ear Trumpet: A funnel-shaped tube of silver, wood, shell, or horn that, when placed in its wearer’s ear canal, raises the apparent volume of sound. A character using an ear trumpet gains a +2 bonus to proficiency throws to hear noise. The bonus does not apply to hijinks. Cost: 15gp.
Padded Rigging: A series of belts, straps, pads, and harnesses designed to keep items securely fastened and protectively enclosed. A character wearing padded rigging can ignore up to 1 stone worth of equipment for purposes of the encumbrance and thievery rules. Cost: 5gp.
Padded Shoes: A pair of padded shoes with soft heels that grant a +2 bonus to proficiency throws to move silently. Padded shoes are ruined if worn in badlands, hills, mountains, swamps, or woods, or in water. Cost: 15gp.
Rope, Knotted Climbing: A rope of silk or hemp, carefully knotted at arm length intervals to aid in easy climbing. Any character may climb a knotted climbing rope with a proficiency throw of 2+, adjusted by the better of the character’s Strength or Dexterity modifier. Cost: 2gp.
Thieves’ Tools, Superior: Superior thieves’ tools grant a +1 bonus to proficiency throws to open locks and remove traps. If the thief rolls a natural 1 while attempting to pick a lock, the tools may make a saving throw versus Death (at 1/2 thief’s level of experience) to resist breaking. The bonus does not apply to hijinks. Cost: 200gp.
Thieves’ Tools, Masterwork: Masterwork thieves’ tools grant a +2 to proficiency throws to open locks and remove traps. If the thief rolls a natural 1 while attempting to pick a lock, the tools may make a saving throw versus Death (at the thief’s level) to resist breaking. The bonus does not apply to hijinks. Cost: 1,600gp.
Weapon Blackener: A sealing caulk which, when applied to weapons, permanently darkens their material. The encumbrance of blackened weapons can be ignored when hiding in shadows for purposes of the encumbrance and thievery rules. A pint of weapon blackener will suffice for one two-handed weapon, two one-handed weapons, or twenty arrows or quarrels. Cost: 10gp.
DESIGNER’S NOTES
First, since these rules don’t alter the throw values for the thief skills, they don’t require any changes to the proficiency or class-build system. They also don’t require adjusting the hijinks mathematics, which would be a complex endeavor.
Second, they reduce the frustration resulting from a single point of failure. A thief can now attempt to pick a lock or remove a trap repeatedly, with only time and the risk of damage to the thief or his tools serve as obstacles to repeated attempts.
Third, they introduce relatively low-cost equipment that offers thieves an improved chance of success in their core tasks - picking locks, removing traps, hiding in shadows, and moving silently. However, the equipment does not stack with common magic items (such as wands of knock, rings of invisibility, ropes of climbing or elven cloaks) so it does not increase late-game power very much.
Fourth, they reward thieves for staying light and nimble and differentiate between thieves laden with shiny weapons, loose coin, and creaky armor, and stealthier types.
EXAMPLE in PLAY:
Rollo, a 2nd level thief, wears oiled leather armor, padded shoes (+2 to move silently), and a dark grey camouflaged cloak (+2 to hide in shadows); he wields a blackened long sword and blackened dagger; and he carries masterwork thieves’ tools (+2), grappling hook, and 50’ knotted rope in padded rigging. His encumbrance is 4 3/6. Padded rigging reduces this to 3 3/6. For purposes of moving silently, his encumbrance is 1 3/6 (+4 bonus), for purposes of hiding in shadows it is 3 1/6 (+2 bonus).
Open Locks 15+ (30% success instead of 20% - 1.5x and see below)
Find Traps 17+
Remove Traps 15+ (30% success instead of 20% - 1.5x and see below)
Pick Pockets 16+
Move Silently 10+ (55% success instead of 20% - almost 3x)
Hide in Shadows 14+ (35% success instead of 15% - more than 2x)
Climb Walls 6+
At 1 in 6 every 2 turns, a wandering monster typically results every 12 turns. Let’s use 6 and 12 turns as the number of turns a thief can attempt to open a lock or remove a trap. With 6 tries at 30% success, the thief has an 89% chance of success. With 12 tries at 30% success, the thief has a 99% chance of success. (I have disregard the chance of breakage/setting off the trap).