I just recently finished a game with a Warrior soloing the entire map.
The key items and equipment were the "Maul" Equipment (yes this is an accessory you can only gain from defeating a Quest DLC opponent)
The "Golden Belt" for the 25% aoe damage on each attack making you a formidable fighter.
Any sword with more than 40-50 damage although the best weapon is the one that lets you crit on every hit. That way you can crit maul your way through any opponent. (If you can somehow reach a level above 100 [e.g. using paragon and destiny's gift] the Lightning Hammer which gives +1 lightning damage per level becomes better).
Also important is high Initiative and Nature's Cloak for the magic damage resistance.
A very good shield would include the Shrill Shield or the Sentinel Shield or the Mirror Shield. The first and last of them offer damage return and the 2nd one offers incredible tankiness.
Also important is Lifeleech as you can learn in the Warrior tree so you heal 9 hitpoints per hit, meaning every maul attack is very potent and every counter attack also.
Thats why you also need the counter attack warrior line for the +1 counter attack on any melee weapon.
Make sure you have SOME kind of magic damage available for those pesky "Banshees" be it a weapon with magic damage like the "Blizzard Weapon from the Frost Wildlands" or even only a "Staff of Furnace" of just some kind of magic. You should only equip those for fights with a banshee. Also note that during my playthrough when facing a "lichs army" with a banshee one could kill everything but the banshee and then press autoresolve: You would "lose" the battle if you had no magic equipped, but you would neither take damage nor die and were at the overview map again, ready to equip some magic and refight the banshee.
Also important to note is that you take "Discipline" and magic resistance very often whenever you can. Because if you're hit by either a "web" or "curse" you can easily die. Web disabling doge and curse removing your armor.
Another thing, if you take "Ereog's Token" you can win fights early and easy, because it is just as good as a "mass curse".
Dodge is good, but its not particularly needed since you can maul-reap your way back.
Notice how you need good accuracy for maul, since without it you can only hit about 3-5 times a row if lucky.
For armor the Champions armor is your ultimate goal anything before that should have least amount of -Initiative and or best boni available. There is no particularly good item out there. Although having access to the Altar Leather Armor provides good 50% fire resistance.
Caution: This relies on having Maul ready either via Berserkers sword or the equipment accessory and can really only work if you focus every exp on your hero that is the warrior. Because every skill point is important for him/her.
Beware of units that can kill you with skills before you can kill them most notably a dragon with firebreath and you don't have high enough resistance.