Dexterity

Increased Weapon Damage
Only Dexterity Along with Strength
 * Staff
 * Quarterstaff
 * Shortbow
 * Longbow
 * Crossbow
 * Composite Bow
 * Recurved Bow
 * Thrown
 * Shield
 * Thrust
 * Piercing
 * Spear
 * Flexible
 * Hand to Hand

Casting Speed
Dexterity works based on breaking points for spell speed. Every spell's casting time will affect where its breaking points are, and every breaking point gives a certain casting speed.

By Slajzer Result: 1) There are "breaking points" where your cast speed gets significantly faster. 2) Anything in between these breaking points gives very little or no return. 3) Maybe someone will, but i fail to see a pattern in these breaking points. 4) The breaking points seem to apply to all spells with the same cast time. This is done with 10% templated casting speed. Breaking points: 2.0s ---> 392 dex, 344 dex, 337 dex 2.1s ---> 356 dex, 354 dex, 308 dex 2.2s ---> 374 dex, 368 dex, 320 dex 2.3s ---> 386 dex, 380 dex, 332 dex 2.4s ---> 392 dex, 350 dex, 307 dex 2.5s ---> 362 dex, 319 dex 2.6s ---> 374 dex, 332 dex 2.7s ---> 386 dex, 344 dex 2.8s ---> 392 dex, 356 dex, 320 dex 2.9s ---> 368 dex, 362 dex, 332 dex 3.0s ---> 374 dex, 338 dex 3.5s ---> 356 dex, 326 dex

Note that even one point of dex under your break point will result in significantly slower cast speed than at the break point. These figgures are not approximate, they are absolute.

Block Chance
Dexterity increases your chance to block along with Shield spec. chance = (50 + ((shield - 1) * (10 / 2)) + ((dexterity * 2 - 100) / 4) + (shieldspec * 10)) / 10

Parry Chance
Dexterity increases your chance to parry along with Parry spec. chance = ((dexterity * 2 - 100) / 4 + parryspec - 1) * (10 / 2) + 50) / 10

Alternate formula:

Base parry rate = 5% Parry spec + RR bonus + template bonus / 2 = % chance from skill ((dex X 2) - 100) / 40 = % chance to parry from dex Base + Skill bonus + dex bonus = Total chance

50% cap