Critical Hits

Okay, so I'm a little confused on how criticals opperate when it comes to the chance of getting them.

What I would like to know is what the critical hit rate (Or should I say chance?) is for a weapon at req 17 in a PvP enviroment. (Yes, this mainly concerns Keen Arrow on an ED bar)

Thanks in advance.

Scoring a critical hit

The chance of scoring a critical hit depends on the target's level compared to the attacker's level. For martial weapons, the attacker's rank in the weapon's attribute is also a significant factor. There are also several skills, as well as the assassin attribute Critical Strikes, that influences the chance of scoring a critical hit. The critical hit rate of animal companions is influenced by the Ranger's rank in Beast Mastery, but is not affected by Critical Strikes.

If you strike a fleeing foe in the back, you will always score a critical hit.

I dunno if this helps tyla, it's from the wiki. I'm guessing that you'd have a 17% critical rate at 17 marksmanship.(That's what I thought before i checked wiki btw)

I've checked on the Wiki recently. I assume it's a 17% chance but I just want to confirm my assumption.

Well the unofficial Wiki gives two tables. According to the linear progression, at 17 weapon mastery the crit chance would be 23.6%.
%chance = (mastery)(1.3) + 1.0.

As Taisayacho said, it's closer to 24%, but that is only if you are level 20 and the target is level 20. As they go down in level, your critical hit chances go up, and if they go up in level, your critical hit chances go down.