Secondary professions for a Dervish

Dervish/Warrior

 * Armor-boosting skills in the Tactics line can make good additions for Dervishes.
 * "Victory is Mine!" can combine with condition-causing Dervish attacks.
 * Wild Blow is also very useful, as its drawbacks are easy to avoid, and critical hits are more powerful with a Scythe.
 * Flail and other IAS skills can help overcome the slow attack speed of a scythe.

Dervish Ranger

 * Apply Poison is often used to spread degeneration, but Dervishes have better skills for this purpose.

Dervish/Elementalist

 * The defensive enchantments of the Earth Magic line, such as Armor of Earth, Stoneflesh Aura and Obsidian Flesh, allow exceptional Tanking in the more difficult areas of the game, such as the Domain of Anguish.
 * PBAoE skills such as Aftershock can combine with the Dervish skills that affect adjacent foes, but native dervish skills are generally more effective.

Dervish/Mesmer

 * Signet of Midnight coupled with Sand Shards causes repeated, heavy damage.
 * Epidemic can be used to spread conditions caused by scythe skills.
 * Channeling and Mysticism combine for ample energy for combat casting builds.

Dervish/Monk

 * Mysticism with Protection spells grant massive amounts of energy back from cheap protective enchantments, such as Shield of Absorption and Reversal of Fortune
 * Dervishes have several strong self-healing skills that surpass the Healing Prayers line.
 * Dervishes have few condition handling skills, and can benefit from Mending Touch and other condition skills.

Dervish/Necromancer

 * Like any melee character, Dervishes can benefit from Plague Touch.
 * Tainted Flesh or Poisoned Heart, when combined with any enchantment ending skill, can spread conditions easily.
 * Touch range skills, though tempting, are usually too expensive for a dervish to use effectively.

Dervish/Assassin

 * Shadow stepping Skills such as Shadow Walk are useful to teleport up to casters in the back lines.
 * Shadowy Burden's snaring and armor reduction effects combine well with Vow of Strength.
 * Dash can be used as a no-attribute speed boost.
 * Daggers generally do not provide sufficient DPS when separated from Critical Strikes, and should be avoided.

Dervish/Ritualist

 * Sight Beyond Sight is often paired with Extend Enchantments for immunity to blind.
 * Sparing use of weapon spells, such as Splinter Weapon, can be effective for a scythe specializing dervish, but are easily outpaced by a Ritualist primary.

Dervish/Paragon

 * A Dervish can quickly charge adrenaline based skills by hitting multiple targets with their scythe. This tactic depends primarily on a cluster of foes, and only fully effective in PvE situations.