From Diablo Wiki
A Battle Mage is a variant, a caster-type character who goes with heavy armor and a melee weapon and fights the enemies toe-to-toe. This sort of character build is created by players who want a challenge, or just some variety in their gaming. It generally takes a very specialized character design, with unusual skills and stats, along with special equipment selected for the purpose.
These types of builds are highly item-dependent, and often benefit from or actually require some specific unique or set items to function. Such items in Diablo II often granted the skills of another class, such as adding an aura or a melee attack skill far more powerful than anything the Necromancer or Sorceress had in their own skill tree.
The Diablo III team has said that they will not be enabling cross-class skills from items, (at least not until they increase item variety in an expansion) so aspiring melee Wizards or Witch Doctors shouldn't count on finding a legendary axe that grants them Cleave or Whirlwind or Lashing Tail Kick or Seven Sided Strike.
There are also going to be class requirements for many items in Diablo III, which will further limit the weapon options for casters trying to fight in melee mode.
That said, very little is yet known about item mods and weapon types, so this question can not be adequately addressed until after the game's release, when much more will be known about the item options.
Battle Witch Doctor
There are not any Witch Doctor skills or Witch Doctor traits specifically designed for a melee style WD. It may still be possible, with special equipment, but the developers don't seem to have included that sort of build in their plans. Players will surely find some skills and traits that lend themselves to it, all the same.
Unlike the Witch Doctor, the Wizard clearly received some Battle Mage skills and traits in the class design. These are abilities that may be of use to regular spell-casting Wizards, but that will clearly work in a special fashion for melee builds.
Wizard Skills: A few of obvious utility for a Battle Mage.
- Frost Nova -- Freezes all enemies in range.
- Ice Armor -- Increases the Wizard's Armor and freezes (+cold damage) melee attackers.
- Diamond Skin -- Absorbs all damage for a limited duration.
- Magic Weapon -- Imbues the Wizard's weapon with magical energy, granting increased damage. (Unknown runestone effects, but imagine multiple hits, elemental damage, +damage, and more.)
Wizard Traits: A few of obvious utility for a Battle Mage.
- Toughness -- Increases Vitality.
- Prismatic Cloak -- Increases the effectiveness of Ice Armor and Storm Armor
- Intimidation -- Increases damage done.
- Weapon Master -- Increases damage done by spells and weapons when the Wizard is wielding a sword, axe, or mace.
- Blur -- Reduces damage taken from melee attackers.
- Conjured Armor -- Increases armor by 25%, or 50% if Ice Armor is active.
- Flight Before Fight -- Increases movement speed when the Wizard is blocked in melee.
- Black Ice -- Frozen targets take 25% more damage from all sources.
Some interesting combinations can be achieved with these options.
For defense, Ice Armor (skill) will be mandatory, for the +Armor and the cold damage/freezing attackers. Prismatic Cloak (trait) and Conjured Armor (trait) both boost the defense of Ice Armor, and then Black Ice (trait) causes frozen targets to take more damage. So Ice Armor will greatly boost the Wizard's defense, and the monsters that do get in hits will be frozen, making them ripe for the kill thanks to Black Ice.
For offense, a Wizard using Magic Weapon, enhanced by the Intimidation and Weapon Master, plus the unknown Runestone bonuses, would be potentially quite effective. Not as powerful as a Wizard using spells in the normal caster style, but that's not the point of a Battle Mage. The object is to be effective with an unusual build, and it seems quite doable, even judging from this early information.