Meditations on the Words of Power

Paarthurnax at the Throat of the World can help the Dragonborn meditate on three Words of Power: Fus, Feim and Yol. There can be only one attribute at a time, though the Dragonborn can repeatedly change the attribute by meditating again as needed.

Effect

 * Fus (force) will apply the effect Force Without Effort, giving a 25% increase in stability against staggering and a 25% chance of opponents being staggered (Most recommended as by the time you reach Paarthunax, you will have learned all words of power for Unrelenting Force).
 * Applies to most attacks with a stagger effect, such as Power Shot, Power Bash, regular power attacks, Unrelenting Force and Shield Charge (when the enemy is not knocked down).
 * It does not function with the Destruction school perk Impact. It achieves its stagger effect through damage inflicted by a particular spell.
 * Stacks with the Heavy Armor perk, Tower of Strength for 75% less stagger. This reduced stagger applies to Dragons landing/crashing near the player, resurrected dragons bursting from a burial mound, regular power attacks by foes, some traps and enemies who use shouts.
 * Feim (fade) will apply the effect Ethereal Spirit, increasing health regeneration while ethereal by 25%.
 * Only applies to the Become Ethereal shout.
 * Can be used by those with vampirism as a means of regenerating health, even in sunlight.
 * Yol (fire) will apply the effect The Fire Within, increasing the damage dealt by Fire Breath by 25%.
 * This increase is questionable against higher level opponents or at higher difficulties where the damage is still minimal when facing enemies with sizable health bars.
 * Weakness to Fire poisons can be applied to an enemy or placed in their pockets to drastically increase the viability of this choice.

Bugs

 * Selecting "Feim" may not add the Ethereal Spirit perk and instead have no effect.  The ability may only show in active effects while Ethereal.
 * Sometimes selecting "Yol" adds a 25% bonus to all fire damage done by the player, not just from the Fire Breath shout. This can be combined with Augment Fire perks, the Vampire/Necromage perk exploit, and Ahzidal's mask to gain huge bonuses to fire spells, with the Flames spell dealing up to 20 fire damage per second.