The ranger/assassin combo is one of the premade ones. With a little adjustment it can be made into a deadly PvP machine.

Skills
Firstly 5 skills to deal a hell of alot of damage in a short amount of time:

1) Jagged strike (lead attack): Nice and cheap with a quick recharge also makes them bleed which is bonus.
2) Fox fangs (off-hand attack): Again nice and cheap with a quick recharge.
3) Horns of the Ox (duel attack): This skill is very important as it knocks the target down ready for the next skill, as a bonus it does a nice lot of damage.
4) Falling spider (off-hand attack): Again a nice skill with loads of damage and as a bonus poisons the target for a good long time.
5) Death blossom (duel attack): Loads of damage again with a bonus of surrounding damage too.

Secondly a mixture of healing, defense and running skills (I pick 3 out of these 4 depending on what kind of mood I'm in):

*) Shadow refuge (enchantment): Boosts your health quite nicely with that added health boost if you're attacking.
*) Whirling defense (stance): Stop all those big fat warriors knocking on you as well as redirecting projectile attacks.
*) Lightning reflexes (stance): Again another skill to stop them pounding on you with the bonus of increased attacking speed.
*) Escape (stance): Running skill with the bonus of evading stuff again.

Armor
-Obviously a hunters mask since all you are using from ranger skills is Expertise.
-Then whatever kind of rune you want to increase your expertise further (I normally go for the major).

Weapons
This is obviously a dagger build so some daggers:
-Poisonous Dragon Fangs of Daggar Mastery (preorder daggers): The increase in daggar mastery is a bonus. The extended poison is a must have for when you use falling spider.
-Ceremonial Daggers (end-game daggers): Increase in health helps quite a bit as well as the extra damage. The energy on every hit allows you to almost never run out of energy since you're pounding on them fast and constant. The high dagger mastery also helps to get the energy since there's more chance of landing a double hit.
Obviously swap out the Ceremonial daggers when not attacking so you have a normal energy regen.

Attribute points
-Normally spread between Daggar Mastery and Expertise.
-If you're using Shadow refuge then at least 8 on Shadow Arts (to get that +8 regen) then the rest spread between the other two.

Use
Charge in and follow the five attack skills off in order. If you start getting worried about your own health while you're attacking start using some of the thos defenses. By the time the first five skills are off your target should be bleeding and poisoned and nearly running away. Keep hitting them until they run. When they start to run shove on your running skill, catch up with them, knock them down with the third skill then finish them off with 4 and 5.

Cons
Obviously being a ranger you don't have nice big tough armor like a warrior nor do you have bonus of the Assassins Critical Strikes which could help. Watch out when you're attacking a group since Horns of the Ox won't knock your target down. When in groups use 1,2 and 5 until your target is seperated. The falling spider can only be used when the target is knocked down so skills 3 and 4 are pretty pointless if you're fighting a group.

Pros
This is one powerful build. I'd say about 80% of the time I can take on a warrior 1v1 and the warrior will be the one running away. The good thing is with the running skill and the knock down skill you can pretty much finish him off if he runs. The main thing that keeps the warrior from hurting you are the 2 defense skills and the run skill, with all of these you have 48seconds of 75% chance to block or evade (with a major rune). This should be plenty of time to destroy most targets. Most warriors are not expecting a ranger in a melee combat situation so will not be prepared for you with this build.

My favourite part of this build is watching big tough warriors running away from a puney little girl ranger.

Any questions or suggestions are more than welcome.