Any and all co-GMs have equal authority with me.
I won't say no OP characters, as I don't think there's a power limit in SAO. However, I will say this: we're starting from the very beginning. Everyone will be pretty weak at first, so no one-shotting everything.
Characters may argue; authors may not.
No killing without author's permission.
You may have as many characters as you can handle.
And of course, have fun!

Combat -

Piercing / Blunt: Bonus damage to armored units

Find weakness: Bonus damage against unarmored units

Enhanced aim: Accuracy bonus to bows

Precision: Weapons have higher critical chance

Cleave: Weapons strike additional targets behind original target

Unguarded: Bonus damage to 1-h weapons if not using a shield or offhand

Flame touched: Sword art skill uses fire damage
Sword art skill has passive cleave for duration

Thunder touched: Sword art skill uses Thunder damage
Sword art skill has a chance to cause [Paralysis]

Frost touched: Sword art skill uses Ice damage
Sword art skill slows attack speed / movement speed by 20%

Suppression: Sword art skill has a chance to cause [Paralysis]

Blade mastery: Bladed weapons deal more damage

Blunt mastery: Blunt weapons deal more damage

Vampirism: Sword art skills have lifesteal

Cold blooded: Party members gain increased damage

Efficient: Sword skills cost less SP

Veteran: Damage+ / critical+ / attack speed+ (Available at lvl 35)

Defensive -

Iron fortress: Increased armor / reduced damage (25%)
(Only for tower shields)

Shield wall: Reduced damage from all attacks (15%)
(Usable with any shield)

Unbreakable: Reduced damage from piercing / blunt attacks

Thorns: Minor damage returned to attacker

Juggernaut: Increased health regeneration

Inspiring presence: Party members gain increased defense

Veteran (Defensive): Armor+ / movement speed+ / Damage reduction+ (Available at lvl 35)

Merchant -

Bargain: NPC vendor pays 10% more / sells 10% cheaper

Haggler: NPC vendor pays 15% more / sells 15% cheaper

Master Trader: NPC vendor pays 20% more / sells 20% cheaper

Legend: NPC Vendor pays 25% more / sells 25% cheaper

Gathering -

Scavenger: More materials from Nodes

Lucky find: Chance to find rare material from mobs

Experienced: Double material from nodes