In Keyword Design, I use a single word as inspiration for a mundane item, a magic item, a feat, a spell, and a class option. Today’s word is “power” as suggested by Aaron.

I was intimidated that today’s word might be too versatile, leaving me stumped for inspiration. How wrong I was. Hopefully you can handle options with this much power!

Power
TYPE	NAME	DESCRIPTION
Mundane Item	Gnome Gyroscopic Human Exoskeleton	Harnessed stilts that increase speed and carrying capacity.
Magic Item	Encyclopedic Weapon	A magic weapon property that teaches the weilder about the target.
Feat	Powerful Presence	Make a Strength or Intimidate check to aid another on Charisma-based skill checks.
Spell	Siphon Sphere	Absorb the magical power of spells cast around you to increase the potentcy of the spells you cast.
Class Option	Blood Shifter	Take on aspects of those whose blood you’ve drawn.

New Mundane Items
GNOME GYROSCOPIC HUMAN EXOSKELETON
Cost: 1253 gp Weight 150 lb

Shafts, gyros, and belts surround two small platforms halfway up artificial legs and rounded leather padding. When a small humanoid creature dons a Gnome Gyroscopic Human Exoskeleton, their land speed increases by 10 feet (to a maximum of 30 feet), and they gain a +4 bonus to Strength and count as a Medium creature for the purposes of carrying capacity. When worn, the weight of the Gnome Gyroscopic Human Exoskeleton does not count against the creature’s load, except when swimming or climbing.
Moving in a Gnome Gyroscopic Human Exoskeleton is challenging. A creature wearing a Gnome Gyroscopic Human Exoskeleton cannot take the attack action, and must make Concentration checks to cast spells as though they were moving vigourously.
Donning a  Gnome Gyroscopic Human Exoskeleton takes 1 minute with an assistant or 10 minutes without. Removing it is a move action.

Above all else, I will be remembered for my mechagnome contributions.
So the first definition of power I knew I had to touch on was physical might. To a gnome, that means looking enviously at their naturally ¼ stronger Medium allies.
So, why the weird price? Gnomes.

New Magic Item
ENCYCLOPEDIC WEAPON
DESCRIPTION
On a successful attack, an encyclopedic weapon reveals additional information about its target as though its wielder had successfully used the appropriate Knowledge skill to identify a special power or vulnerability. The wielder gains additional information for every successful attack with the encyclopedic weapon, even if they have already made a Knowledge check about that creature.
CONSTRUCTION REQUIREMENTS
Moderate conjuration; CL 8th; Craft Magic Arms and Armor, blood biography; Price +1 bonus.

Because knowledge is power!

New Feat
POWERFUL PRESENCE
Your muscles support your allies’ arguments better than your mouth ever could.
Prerequisite: Str 13
Benefit: You can aid your allies’ Bluff, Diplomacy, or Intimidate checks with a Strength check. If you have Intimidating Prowess, you can instead aid your allies’ Bluff, Diplomacy, or Intimidate checks with an Intimidate check.

This combines power over others with another round of physical power. It’s also from personal experience. I’m a big guy with a deep voice, and when I get into a topic I get louder and speak physically. People back down from what I’m saying when what I really want is to engage with them.

New Spell
SIPHON SPHERE
School abjuration; Level cleric 5, magus 5, sorcerer/wizard 5
CASTING
Casting Time 1 standard action
Components V, S
EFFECT
Area 30 ft. diameter sphere-shaped emanation centered on you
Duration 10 min./level (D)
Saving Throw none; Spell Resistance no
DESCRIPTION
A magical bubble around you absorbs the slivers of the residual potency of spells cast within it. When a spell is cast within the area of this spell, you gain a number of temporary siphon points equal to the level of the spell cast. You can use these siphon points to spontaneously add the effects of metamagic feats you know to spells you cast for the duration of the spell. It costs a number of siphon points equal to the number of spell slot higher than the spell’s actual level the modified spell takes up.
Siphon points do not stack. When a new spell is cast within your siphon sphere, the siphon points either replace your current siphon points if the number of siphon points you currently have is less than the level of the spell, or the siphon points are lost if the number of siphon points you currently have is greater than the level of the spell.

Confession: I don’t like how area/range/target works on Pathfinder spells. I don’t know if I should have listed the range as 30 ft and the area as a sphere centered on you, or if I shouldn’t have listed the shape of the emanation if it’s supposed to be a circle. I find the way these stats are described in the magic chapter inconsistent with how they are implements in the spells chapter.

New Class Option
BLOOD SHIFTER (Shifter archetype)
Everything that makes up a living creature is contained in their blood. When blood shifters get their hands on a living creature’s blood, they can tap into a little bit of who their victim is and change their shape to match it.
Alignment: A blood shifter must be chaotic. This alters a shifter’s alignment restriction.
Bleeding Rend (Ex): When a soul shifter successfully hits the same target with both its claw attacks in the same round, the target suffers 1 bleed damage.
This replaces a shifter’s wild empathy.
Blood Aspect (Su): When a soul shifter deals bleed damage to a living creature (with bleeding rend or another ability that causes bleed damage), she can temporarily adopt one of the following of her target’s aspects as an immediate action:
Ability Aspect: The blood shifter gains access to one of the target’s extraordinary, spell-like, supernatural, or untyped abilities, such as rage or sneak attack, for 1 round. She uses this ability as the creature she gained the ability from. Using an ability that is limited to a number of uses per day uses up an additional use of blood aspect.
Attack Aspect: If the target’s highest to hit modifier if higher than the blood shifter’s to hit modifier with her shifter’s claws, her to hit modifier with her shifter’s claws increases to match the target’s highest to hit modifier for 1 round.
Defensive Aspect: If the target’s Fortitude, Reflex, or Will saving throw, or it’s Combat Maneuver Defense, one of the blood shifter’s saving throw or her CMD increases to match her target’s for 1 minute.
Feat Aspect: The blood shifter gains access to one of the target’s feats for 1 round. She uses this feat as the creature she gained the ability from. Using a feat that is limited to a number of uses per day uses up an additional use of blood aspect.
Magic Aspect: If the target can cast spells, the blood shifter gains access to the target’s spell list for 1 round. She casts as the target she gained the spells from. Casting a spell uses up a number of additional uses of blood aspect equal to the spell’s level (minimum 0).
Size Aspect: If the target is at least one size category smaller than the blood shifter, she can reduce her size by one category, as reduce person, for 1 minute. If the target is at least one size category larger than the blood shifter, she can increase her size by one category, as enlarge person, for 1 round.
If she hits the same target multiple time, she can gain multiple aspects of that target, including defensive aspects. Each aspect she adopts uses one of her daily uses of blood aspect. A blood shifter can use blood aspect a number of times per day equal to 3 + her shifter level. At 9th level, when a blood shifter uses her blood aspect ability, she can choose two of her target’s aspects to adopt with a single use of that ability. At 14th level, she can choose up to three of her target’s aspects to adopt with a single use of that ability.
This replaces a shifter’s shifter aspect, Chimeric Aspect, and Greater Chimeric Aspect.
Cauterize (Ex): At 3rd level, a blood shifter becomes immune to bleed damage.
This replaces a shifter’s woodland stride.
Blood Shape (Su): At 4th level, when a soul shifter deals bleed damage to a living creature (with bleeding rend or another ability that causes bleed damage), she can temporarily become an exact replica of the target, taking the target’s shape and appearance and gaining access to all of the creature’s abilities for 1 minute. This is a polymorph ability. A blood shifter can use this ability once per day, plus an additional time per day at 6th level and every 2 levels thereafter, for a total of eight times per day at 18th level.
Absorb blood (Su): At 5th level, a blood shifter can choose a target they’ve dealt bleed damage to in the last minute. Once in the next 24 hours, they can use blood aspect as though they just dealt bleed damage to that target this round.
This replaces the shifter’s trackless step ability.

Wow, already a shifter archetype? This idea started as a monk archetype, but I’ve already done a monk. Before doing a second monk archetype, I checked to see if the concept worked for a class I hadn’t done yet and lo and behold; a shape shifting melee class was just introduced to the game.

Thanks again to Aaron for the keyword suggestion. If you have thoughts on the balance and use of these abilities, or you would like to offer a single word that you think can inspire a mundane item, a magic item, a feat, a spell, and a class option, let me know in the comments below.