Warrior either dual wield two swords or offhand shield.
Dual swords offers better DPS while shield offer a lot of Defense and Magic Resistant, also with Elemental resistant against Elemental runes.
Its based on the personal preference of the Warrior to wether go for offensive build or defensive build to adjust the weapon correctly.
Instance weapons for Warrior are good but not exceptionally useful because often time, warrior will not rely on raw DPS to win the fight, thus making HP leech less useful.
Warrior use heavy armors with the higest P-Def and lowest M-Def in the game. This means Warrior is very vurnable to Mage in general.
Instance armors for Warrior are fairly weak and awful compare to Mage and Assassin's ones, It only offers HP, mediorcre Str and Sta, and the useless M-Def (which doesn't matter since Mage will likely to hurt you with their Armor Ignore attacks most of the time, hence M-Def is useless).