Warrior is a very solid class among all classes in this game. Although warrior normally may not be able to produce the highest damage output in comparison to all other classes, or provide effective support abilities, it is the most resistant class of all classes. Warrior also has decent overall attack damage due to his weapon expertise skills.
(expertise skills doesn't scale with strength, and only scales with weapon damage, with assassin's unarmed expertise as an exception, which scales with strength and the character's base damage)
As higher health makes the character more likely to be hit by enemies, and that warrior is most resistant class of all classes due to a warrior class skill called "Mind of Steel", warrior can provide decent protection for other party members if some points are invested in strength.
The warrior's Mind of Steel passive and weapon expertise skill makes warrior one of the best class to solo this game with (playing with only 1 character without a party). The massive amount of resistance provided by Mind of Steel will eventually help warrior neglect many elemental damage, and most importantly, cold damage, as cold damage from mobs can often freeze characters.
(If one is soloing this game, mobs with cold damage can sometimes "prema-freeze" the character, as freezing a character no only prevents the character from taking action, but also reduces the character's defense to make the character more vulnerable to freezing during the time the character is frozen. This makes it possible for a mob to prema-freeze a character without the consumable: medicine.
Most of a warrior's skill are passives and physical damage active skills that scales with the warrior's auto attack damage. Moreover, there are also two support abilities, in addition to one insanely high damage damage over time spell. Thus, this forces all warriors to take the build path of either an Off-Tank or Tank
Because warrior has four weapon expertise passive to choose from, mastering them can help boost warrior's damage output. However, because these passives only scales with the damage from the weapon, but not the character's own base damage, it doesn't scale with strength. This greatly cuts the warrior's damage output potential.
As an off-tank, good places to invest points in are Strength, Mind of Steel, Any weapon expert passive, Hard Impact, and possibly Round Strike (with Mind of Steel and a weapon expert passive as the most important skills to level). Regeneration can also be a good place to invest points in if your warrior uses alot of special attacks.
As an off-tank, one of the most important skill to max out is "Mind of Steel". While providing two points of resistance per level may not seem a lot, as the character levels up, it can sum to become massive amount of resistance. This allows the character's defensive equipment to focus more on offense and armor, as "Mind of Steel" often provides enough resistance to neglect most elemental damage (especially in a solo character case, where the character levels faster due to having no one else in the party to share the exp)
The build is very similar to that of an off-tank. However, instead of focusing on damaging abilities, Knock Back, True leader, blood brother are focused on, in addition to maxing Mind of Steel and investing in high amount of strength.
This is build would only work if the character is in a party of at least two, as True Leader would be too ineffecient to invest points with only one character in a party, and blood brother would not work without another character in the same party.
There is this one ability, Totem of Pain, that has incredibly high damape output. Although it may cost alot of mana after investing a few points, the build can work if the character invest some points on constitution. As a result, a caster build can be made by through saving up points for totem of pain until level 7, and investing points into constitution in addition to regeneration, and maybe, Mind of Steel.