Secondary professions for a Warrior

Warrior/Ranger
Melandru's Resilience is highly effective in combating hexes and conditions. Serpent's Quickness can be useful with shouts and some attacks with long recharge times.

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 a AoE snare to keep groups of enemies from kiting as efficiently.

Warrior/Mesmer
Wise use of Physical Resistance or Elemental Resistance can allow the W/Me to tank more efficiently than any other profession combination.

Warrior/Monk
The game's most popular combination, the W/Mo benefits from the superior armor of the Warrior and the condition and hex removal skills of the Monk.

Mending Touch, Purge Signet and Empathic Removal are good utility skills expanding the warrior line.

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

Warrior/Assassin
The Assassin has a wide range of snares and shadow steps that can serve a Warrior well. Death's Charge is Useful for closing the distance in preparation for an adrenal spike. Shadow Prison has an added snare. Signet of Malice can provide free condition removal.

Iron Palm can be an alternative to Shock. Consider using Sever Artery - Iron Palm - Gash - Final Thrust as a spike.

Warrior/Ritualist
Sparing use of Weapon skills can benefit a Warrior; Splinter Weapon can be combined with Triple Chop or Hundred Blades. A Ritualist primary, however, does this job better.

Warrior/Paragon
Remedy Signet may be used with no attribute points for a quick, energy-free method of condition removal.

Warrior/Dervish
The Warrior can make use of many of the Dervish's cheap Enchantments to add types of damage and other effects to his attacks, or to increase his defense. 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.