Secondary professions for a Warrior

Warrior/Ranger

 * The Ranger line offers a few alternative IAS skills.
 * Some of the preparations from the ranger affect melee skills (Such as apply poison) allowing effects that would not otherwise be accessible.

Warrior/Monk

 * Skills such as Mending, which has a small return for a high cost of attribute points and Orison of Healing, which is a mediocre heal, should be avoided.
 * Mending Touch is a useful form of condition removal, even with little or no attribute point investment.
 * Supporting skills such as Vigorous Spirit provide excellent healing over time, allowing the Warrior to keep on fighting. In addition, Vigorous Spirit can combine well with Cyclone Axe and Triple Chop.

Warrior/Necromancer

 * The most common usage of the Necromancer secondary is for condition removal via Plague Touch.

Warrior/Mesmer

 * Wise use of Physical Resistance, Elemental Resistance or elemental mantras can add additional survivability to solo or tanking builds.

Warrior/Elementalist

 * Shock can be used as a snare and interrupt, however exhaustion will certainly be felt with a Warrior's low energy pool.
 * Grasping Earth can be used as an AoE snare to keep groups of enemies from kiting as efficiently.
 * The conjure skills, such as Conjure Frost can provide additional damage when wielding an elemental weapon for a very small investment of energy.

Warrior/Assassin

 * The Assassin has a wide range of snares and shadow steps that can serve a Warrior well. Shadow Prison is an outstanding skill in this vein.
 * Signet of Malice can provide free condition removal.
 * Dash is an excellent speed boost that also serves as a quickly recharging cancel stance for Frenzy.
 * Death's Charge is useful for closing distance in battle, but take care not to outrun your party's support.
 * Disrupting Dagger is a useful interrupt which cannot be blocked or miss.

Warrior/Ritualist

 * Sparing use of Weapon skills can benefit a Warrior; Splinter Weapon can be combined with Triple Chop or Hundred Blades. Ritualist primaries, however, far outclass Warriors at spamming weapon spells.

Warrior/Paragon

 * Warriors and Paragon Skills have very little Synergy.

Warrior/Dervish

 * A scythe can work in a Steady Stance/Drunken Blow/Desperation Blow build.
 * Many Scythe Mastery skills are general-purpose Melee Attacks (i.e. Rending Sweep) rather than weapon-specific skills, which allows them to be used with axes, hammers, and swords.
 * Rending Touch can be used as an enchant removal.
 * Pious Haste can be used as a cancel-stance for Frenzy.