Secondary professions for an Assassin

Assassins are highly aggressive, focused damage dealers, better for hit and run skirmishes then drawn out tanking or back-line sieges.

Always remember, when choosing secondary skills, that native skills often have better synergy with the profession's purpose, interact better with the profession's other skills, and benefit from runes.

Assassin/Warrior

 * Assassins do not have any attack speed enhancing skills (Excluding the PvE/Nightfall-only Critical Agility). Flurry, and Tiger Stance can increase the rate they can pull off an attack chain, as well as increase their overall DPS.
 * Wild Blow to cancel important stances.
 * Daggers' ability to double strike allow massive use of adrenal skills like "Fear Me!".

Assassin/Ranger

 * Barrage damage can be improved with high critical strikes attributes, adding bonus damage to attacks, energy management, and effects from skills like Critical Eye, if you use Barrage with Sharpen Daggers, you can also spread bleeding.

Assassin/Monk

 * Vigorous Spirit can be a very effective self-heal due to the Assassin's ability to hit quite rapidly. It is especially useful when paired with Locust's Fury and Critical Agility.

Assassin/Necromancer

 * Assassin and Necromancer Skills have very little synergy.

Assassin/Mesmer

 * Arcane Echo can be used to chain Shadow Form when running or soloing.

Assassin/Ritualist

 * Sparing use of weapon spells such as Warmonger's Weapon can aid an Assassin in battle, although weapon spamming is best left to Ritualist primaries.

Assassin/Paragon

 * Assassin and Paragons skills have very little synergy.

Assassin/Dervish

 * In PvE, Critical Agility, Critical Eye, Aura of Holy Might and Vow of Strength can be used with a scythe to inflict considerable damage.