Converting magic weapons from D&D to Savage Worlds is a subject that's been raised on a number of occasions, particularly by people who are interested in adapting various campaign settings and Adventure Paths.
I've discussed my ideas for weapon conversions in general terms in the past, however my upcoming Vancian magic system needs something more concrete (particularly for the artificers), so I decided it was time to flesh out some actual guidelines.
Most magic weapons in D&D have a simple fixed bonus in the range +1 to +5, which is applied to both attack and damage rolls. However Savage Worlds is far less granular, and even +1 to attack and damage is a very potent bonus, so here is the approach I recommend.
+1 Weapon: +1 damage on a raise.
+2 Weapon: +1 damage.
+3 Weapon: +1 to attack rolls.
+4 Weapon: +1 to attack rolls and +1 damage on a raise.
+5 Weapon: +1 to attack rolls and +1 damage.
This is also consistent with the weapon ability prices listed in Savage Armoury. Note that if you're using Savage Armoury as well, an enchanted weapon should always have the Masterwork weapon ability.
The following are some proposed conversions of the special weapon abilities used in D&D. The goal is to retain the general flavour of the original ability, while significantly toning down the mechanical benefits to match those described earlier. These also reference certain monstrous abilities (such as alignment-based abilities for supernatural creatures) which I use in my monster conversions - if you don't use those monstrous abilities, you can just base it on GM's discretion (which is how "good" and "evil" are normally defined in the core rules for the purposes of Edges such as Champion and Holy/Unholy Warrior).
Anarchic (+2): This weapon has been infused with the power of chaos. It counts as Chaotic for the purposes of Physical Resistance, and also inflicts +2 damage to creatures with the Lawful ability.
Axiomatic (+2): This weapon has been infused with the power of law. It counts as Lawful for the purposes of Physical Resistance, and also inflicts +2 damage to creatures with the Chaotic ability.
Bane (+1): This weapon is designed to kill a specific type of foe, such as humans, elves, dragons, etc, chosen when the weapon was forged. It inflicts +2 damage to creatures of the chosen type.
Brilliant Energy (+4): The striking part of this weapon has been transformed into intense light, causing it to illuminate an area the size of a Large Burst Template when drawn. This weapon ignores armour, as well as Parry bonuses from shields and weapons, but can only harm living matter; it inflicts no damage to undead, constructs, or inanimate objects.
Dancing (+4): As a normal action you can release this weapon from your hand, causing it to float beside you and fight your enemies. This is resolved as if you had a free attack at -2 each round; this must be a normal attack. You can grasp the weapon in your hand again as a free action, deactivating its Dancing power. You can only activate one Dancing weapon at any one time, and if you draw Clubs for initiative while the weapon is already active, it will automatically return to your hand at the end of your turn.
Defending (+1): The wielder of this melee weapon can use the Defend maneuver as a normal action if they wish, allowing them to perform other actions on the same turn (with the standard multiaction penalty).
Disruption (+2): This weapon inflicts +2 damage to undead, and if they are incapacitated by the attack they are automatically destroyed.
Distance (+1): This ranged weapon has its base range increased by +1/+2/+4 (missile weapons that use Shooting typically have their base range doubled, or tripled if they require both hands to use, see Savage Armoury for details).
Flaming (+1): This weapon bursts into flames on command as a free action. While flaming, the weapon illuminates an area the size of a Medium Burst Template, and any flammable targets struck by the weapon must roll to see if they catch fire. The damage caused by this weapon can be treated as either physical or fire, whichever is most effective against a particular foe.
Flaming Burst (+2): This weapon works like a Flaming weapon, except that when it hits with a raise it also explodes with flame, inflicting +d10 fire damage instead of the normal +d6 damage (the bonus die is always fire damage).
Frost (+1): This weapon becomes coated in frost on command as a free action. While frosty, the weapon gains AP 1. The damage caused by this weapon can be treated as either physical or cold, whichever is most effective against a particular foe.
Ghost Touch (+1): This weapon is capable of harming both ethereal and non-ethereal creatures. It can also be picked up and wielded by ethereal creatures.
Holy (+2): This weapon has been infused with holy power. It counts as Holy for the purposes of Physical Resistance, and also inflicts +2 damage to creatures with the Evil ability.
Icy Burst (+2): This weapon works like a Frost weapon, except that when it hits with a raise it also explodes with frost, inflicting +d10 cold damage instead of the normal +d6 damage (the bonus die is always cold damage).
Keen (+1): This piercing or slashing weapon is particularly sharp. If it hits with two or more raises, it inflicts a further +d4 damage (on top of the standard +d6 damage for a single raise).
Ki Focus (+1): This weapon channels the wielder's ki. If the wielder has the Adept Edge, and uses it to gain AP 2 until their next action, the AP applies to attacks made with this weapon in addition to unarmed attacks.
Merciful (+1): This weapon can be used to inflict nonlethal damage without incurring a penalty to the attack roll.
Mighty Cleaving (+1): If the wielder of this weapon has the Cleaving Blow Edge, they can now use it twice per round, although not on the same foe.
Returning (+1): This throwing weapon can be summoned back your hand as a action, as long as it's within its maximum range. This is the same as readying a weapon, meaning that if you have Quick Draw you can summon the weapon back to your hand as a free action.
Seeking (+1): This ranged weapon can ignore up to 1 point of attack penalty from cover or concealment (but not both at the same time).
Shock (+1): This weapon becomes wreathed in electricity on command as a free action. While electrified, the weapon illuminates an area the size of a Small Burst Template, and gains AP 1 against metal armour. The damage caused by this weapon can be treated as either physical or electricity, whichever is most effective against a particular foe.
Shocking Burst (+2): This weapon works like a Shock weapon, except that when it hits with a raise it also explodes with lightning, inflicting +d10 electricity damage instead of the normal +d6 damage (the bonus die is always electricity damage).
Speed (+3): This weapon allows you to make an additional attack when using it to perform an attack action. When you use this ability, roll an extra Fighting die with your attack roll, and apply a -1 penalty to all of your attacks for the turn.
Spell Storing (+1): This weapon can store a single Novice or Seasoned spell, which must be cast into it; the caster cannot recover their Power Points until the spell is discharged. Whenever you strike a foe with a raise, you may choose to discharge the spell as a free action instead of adding the standard +d6 damage for a raise. The arcane skill roll for the spell is made when the spell is discharged, not when it is placed into the weapon; if the roll results in Backlash, apply it to the wielder rather than the spellcaster.
Thundering (+1): Whenever this weapon hits with a raise, it releases a thundering roar, inflicting +d10 sonic damage instead of the normal +d6 damage. This sound can be heard from quite a long distance away. Creatures incapacitated by this damage always suffer deafness instead of rolling for a random injury.
Throwing (+1): This melee weapon can now be thrown with a range of 3/6/12.
Unholy (+2): This weapon has been infused with unholy power. It counts as Unholy for the purposes of Physical Resistance, and also inflicts +2 damage to creatures with the Good ability.
Vicious (+1): This melee weapon inflicts +2 damage, but it also inflicts half as much damage to the wielder (rounded down) as it does to the victim - e.g., if you hit someone for 15 damage, you also suffer 7 damage yourself.
Vorpal (+5): This exceedingly sharp weapon inflicts +d6 damage die for every raise on the attack roll (rather than just the first raise). If you incapacitate a foe with a vorpal weapon, they are automatically decapitated.
Wounding (+2): This weapon causes particular horrible wounds; Soak rolls against damage inflicted by this weapon suffer a -2 penalty. Creatures who don't suffer additional damage from Called Shots (such as undead and constructs) are not affected by this weapon.