Written by Wydun, because he loves you.
Sentinel Guide:

Sword Sent: The high offense and high defense sword wielding mofos!!!
Weapons: You have a few options to go. You can go 2-Handed Sword (most common), or 1h + Bow, or even Dual wield if you wanted. All do work but 2-handed sword is the easiest approach.

Statting: Several ways you can build:
1. Strength / Dexterity / Agility:  This build allows all of your sword techs to be useful and actually be able to land. Also your Windslash will have a better chance to land due to the agility.
2. Strength / Dexterity / Constitution: This is the ultimate Anti-Melee build. If you're so against the melee classes take this approach:
3. Strength / Dexterity / Wisdom: This is a general balance build but this build focuses on certain swordtechs, so make sure you learn what swordtechs to use.

Swordtechs: 
2 - Tremor - Semi lags you but stops combat allows you a chance to escape
3 - +100 Dexterity that lasts for roughly 3 ticks
4 - Berserk - It adds stats, very useful to have this always on for the extra stats
5 - Frenzy - Another buff, but also with stats this gives you extra auto attacks
6 - Soulslash - Low damage move 
7 - Shiftslash - Another damage move that instantly hits and cannot be blocked
8 - Lunge - Hits 4 times and does reasonably decent damage
9 - Cleave - A chance to be able to break a limb (it fails a lot)
10 - Omnislash - A 0-7 attack possible, Agility helps this land
11 - Bladedance Tech - The move on this tech is solely based on your bladedance choice, Earth/wind/water/fire all do different moves.

Arcane Sentinel:  The caster hybrid of the Sentinels
Weapons: Dual Wield or 1hand + shield or 2 handed or 1h + Bow

Statting: 
1. Intelligence / Constitution / Wisdom: The well balanced build, defense against both melee and caster.
2. Intelligence / Constitution / Agility: Depending on what skills you like you'll see why agility comes into play.
3. Intelligence / Constitution / Dexterity: This is the Anti-Melee build.

Buffing your character up with spells:
Embrace - Magic Resistance
Blessing - Stat buffs
trace wind self - Some stats + haste
Trace earth self - -Armor Class
Armor - -Armor class
Shield - -Armor Class
Stoneskin - -Armor Class
Giant Strength - Free strength based on your intelligence. 1 str for every 10 intelligence
Thorns - Damages enemies when they hit you
Barkskin - Eats up x amount of damage
Regenerate - Makes you heal a bit faster

Playstyle: 
Playing around with your arcane will be an adventure. You will notice you have a huge amount of abilities you can use. So think nice and hard with all the items your trace command can do. Don't forget 
to use Help Trace for a list of the abilities that each type does.

Bow Sentinel: Pew pew the arrow shooter of the sentinels
Weapons: 1h sword + Bow

Statting: Agility / Dexterity / Strength (intelligence can also be used but it only affects minor affects on quivers)

Skills:
Snipe: An ability to debuff your enemies from a distance
Shoot: Shoot your enemies from a distance (quiver will have different types of arrow and they will change your shoot affects) Also you can use this command once you have your mastery while in combat.

Play style: The playstyle for this class is hard, you're a very much a hit and run type of class. You're more affective out of combat rather than in combat. So don't be discourage if you get caught in 
combat, just learn how to escape and pew pew them more with arrows.