Hit refers to physical damage that occurs as a result of an attack made with melee or ranged weapons. The base chance to miss with maximum weapon skill against an opponent of equal level is 5% for two handed and 24% for dual wield.
Calculating Miss Rate for Physical Damage Attacks
Hit chance decreases chance to miss rather than increases chance to hit. Chance to miss in PvE is determined solely by the difference in the defending mob's Defense Skill and the player's Weapon Skill. Further, the effect is not linear. So, there are actually two different formulas that might apply, depending upon whether the difference between the mob's Defense Skill and your Weapon Skill is greater than 10 or not. Here are the two formulas:
If the difference between the mob's Defense Skill (level * 5) and your Weapon Skill ([level * 5] + additional bonuses) is less than or equal to 10 then the formula for calculating your base miss rate against that mob is:
 5% + (Defense Skill  Weapon Skill)*.1%
 dualwielding: 24% + (Defense Skill  Weapon Skill)*.1%
If the difference between the mob's Defense Skill and your Weapon Skill is greater than 10, then the formula for calculating your base miss rate against that mob is:
 7% + (Defense Skill  Weapon Skill  10)*.4%
 dualwielding: 26% + (Defense Skill  Weapon Skill  10)*.4%
Applying these formulas gives the following base miss rate for a Level 60 character with a 300 Weapon Skill:
* v. Level 60 mob: 5.0% / dualwield: 24% * v. Level 61 mob: 5.5% / dualwield: 24.5% * v. Level 62 mob: 6.0% / dualwield: 25% * v. Level 63 mob: 9.0% / dualwield: 28%
Thus if you are a Level 60 character with a Weapon Skill of 300, you need +9% chance to hit to never miss a shot against a Level 63 boss (or skull mob).
What this means is that there is a big +hit benefit to keeping your Weapon Skill as high as possible for your class/race. For example, by improving your Weapon Skill from 290 to 295, you effectively reduce your chance to miss against Level 61 mobs by 3%! However, after getting to 295, increasing your Weapon Skill the next 5 levels, to 300, only reduces your chance to miss by an additional .5% (or 3.5% in total). Also, note that there is a huge jump in miss rate reduction by going from 294 to 295 Weapon Skill. This is the point where you switch from one formula to the other, and so this particular single point of Weapon Skill is worth a dramatic +1.4% hit against a Level 61 mob.
Racial bonuses provided +Weapon Skill, and thus turned out to be pretty valuable for improving your +hit capability. For Humans, Dwarves, Orcs and Trolls their racial bonuses increased their Weapon Skill at Level 60 from 300 to 305. With a 305 Weapon Skill, your base miss rate against a Level 63 mob (or skull boss) was only 6% instead of 9%.
Melee attacks divide in to two categories: auto attacks (white) and special attacks (yellow). Auto attacks use a one roll table and special attacks use a two roll table. Base chance to miss is the same for both auto attacks and special attacks. Attacking a mob from behind removes parry and block from both tables, provided the attack is more than 0.5 yards
Auto attacks (one roll table)
Each melee auto attack made by characters against mobs will result in one of the following in order of precedence:
Result 

Miss 
Dodge 
Parry 
Glancing blow 
Block 
Critical strike 
Hit 
Increased hit chance can result in increased critical strike results from auto attacks. For example: maximum dual wielding weapon skill, 0% chance to hit, and chance to critical strike 50%. Dual wield auto attacking a raid boss from behind results in a loss of 8.6% critical strike:
Result  Chance 

Miss  28% 
Dodge  5.6% 
Glancing blow  25% 
Critical strike  41.4% 
Hit  0% 
Increase chance to hit to 10% and decrease chance to critical strike to 45% results in no loss of critical strike:
Result  Chance 

Miss  18% 
Dodge  5.6% 
Glancing blow  25% 
Critical strike  45% 
Hit  6.4% 
Special attacks (two roll table)
Each melee special attack made by characters against mobs will result in one of the following in order of precedence:
Result 

Miss 
Dodge 
Parry 
Block 
Hit 
If the result is block or hit, then a second roll occurs to determine critical strike as follows:
 Block: roll for blocked hit or blocked critical strike
 Hit: roll for hit or critical strike
Increased hit chance can result in increased critical strike results from special attacks upon exceeding the base 9% chance to miss. For example: maximum weapon skill (300 at level 60), chance to hit 0% and chance to critical strike 25%. Special attacking a raid boss (level 63 and 315 defense) from behind results 21.35% critical strike (25% of 85.4%). Increase chance to hit to 10% results in 23.6% critical strike (25% of 94.4%).
Note: It is possible and even likely that even yellow attacks use a one roll table, as the white attacks explain above.
See also
 Combat
 Combat rating system
 Attack table
External links
