Diablo III- Skills Article CXXXVI: The Wizard, Conjuration Skills- Magic Weapon

Magic Weapon (25 Arcane Power): For the next 5 minutes, your weapon’s damage is increased by 10%.

Something of a relic, Magic Weapon is leftover from a Beta concept that really didn’t manage to pull itself through to the finished game- the Battle Mage, a Wizard focused exclusively on melee combat.  Part of the reason this doesn’t really work is that even close-range Wizards are unlikely to actually hit anything with their weapon, or try very hard to be in melee range.  The other part of the reason is that this increase to damage doesn’t actually affect most of the Wizard’s skills- only Spectral Blades is confirmed to improve in damage while Magic Weapon is active.  Mind, Spectral Blades is a very strong Wizard primary skill, so if you use that as your main attack, you may find that Magic Weapon is still passably useful.

Electrify (25 Arcane Power): For the next 5 minutes, your weapon’s damage is increased by 10% and your weapon attacks have a chance to send arcs of lightning out to up to 3 nearby enemies, dealing 10% weapon damage as Lightning damage to each of them.

Since you’re more likely to use your Magic Weapon skill to improve your Spectral Blades, this rune is actually useless.  The secondary effect doesn’t trigger on Spectral Blades because you aren’t actually using your weapon for it.

Force Weapon (25 Arcane Power): For the next 5 minutes, your weapon’s damage is increased by 15% and your weapon attacks have a 2% chance to cause knockback.

Forget the knockback.  Not only is the knockback chance indescribably tiny, but you’re not hitting with the weapon- you’re hitting with Spectral Blades.  A rune to increase the benefit of Magic Weapon to a 15% increase in damage isn’t anything to sneeze at, and can make the skill worthwhile- if you lean on Spectral Blades a lot.

Conduit (25 Arcane Power): For the next 5 minutes, your weapon’s damage is increased by 10% and your weapon attacks have a chance to restore 1 Arcane Power.

This rune is useless.  Even if you did attack with your weapon instead of Spectral Blades, 1 Arcane Power per swing is bad, and having it only happen some of the time is worse.  Don’t expect this to be useful even if some form of melee Wizard is enabled.

Venom (25 Arcane Power): For the next 5 minutes, your weapon attacks poison enemies, dealing 15% weapon damage as Poison damage over 3 seconds.

Another useless rune- although if the Battle Mage ever comes back in some form, Venom’s added damage effect could be fairly nice.

Blood Magic (25 Arcane Power): For the next 5 minutes, your weapon’s damage is increased by 10% and your weapon attacks heal you by 1.5% of the damage they deal.

This percentage is too low.  Even if you were to start smacking things with your weapon, 1.5% healing is terrible for a fragile class like the Wizard.  Stick to Force Weapon if you really want to use Magic Weapon to improve your Spectral Blades.