Secondary professions for a Dervish

Dervish Warrior
The Dervish/Warrior Class is a very potent combination. Combining the Dervish Elite Avatars with the Warrior’s melee attacks and stances can make an effective build.

Dervish Ranger
A Dervish/Ranger could use Apply Poison to dish out poison in an area of effect.

Dervish Elementalist
A Dervish Elementalist can benefit from the numerous enchantments (Armor of Earth, etc.) and AoE spells (Aftershock,etc.) offered by his second class to endure and deal more damage in combat and gaining benefit of his Mysticism attribute.

Dervish Mesmer
A Dervish/Mesmer could use illusionary weapon and cause armor ignoring AoE damage

Dervish Monk
Probably this could resolve in a nice combination of Mysticim combined with Protection spells to get massive amount of energy back from your cheap protective enchantments. Contemplation of Purity could quicken this, and since many Dervish enchantments give a Dervish even more health upon ending, incredible spike heals and conditon removal is possible. You can also use skills such as Vigorous Spirit in conjuction with any Scythe Mastery skill- Dervish Scythe Mastery skills hit up to 3 adjacent opponents, so as you would get massive amounts of health from Vigorous Spirit. This could be very effective in farming.