I fucking suck at this game.
Always, with my Warrior, I'm running out of cards mid-game, and the opponent always seems to have 2-3 more cards than me. So I always have unused mana. I'm putting 'draw' cards in my deck, but I suspect it has more to do with my playstyle.
You underlined a basic problem with the Warrior deck. My Warrior is level 40, so I've done my fair share of games with him. The issue is that you often need 2 cards to do the same job where other decks will only need one. The weapons help to balance things out a bit; Fiery War Axe can remove two minions with 3 health each, which is huge value for 2 mana. The only downside is that you take damage from the minions.
Because the Warrior's card draw is fairly limited, you should think in terms of
card efficiency as much as
mana efficiency.
Good card efficiency spells:
Battle Rage (you'll usually get at least 2 cards out of this one)
Commanding Shout (amazing if any minion is prevented from dying)
Heroic Strike (outstanding in any situation)
Cleave (if it removes even one minion, but preferably two)
Brawl (if you are overwhelmed by minions)
Mortal Strike (removes many high-value cards, especially if you are at low health)
Upgrade (self-explanatory)
Shield Block (extra HP and a card)
Bad card efficiency spells:
Charge (rare for it to save you from spending cards)
Execute (limits the enemy's ability to trade more than 2 for 1, but you will ALWAYS have to trade 2 for 1 at a minimum)
Inner Rage (sometimes worth it to use with Enrage cards, but it also makes it easier for the enemy to trade up)
Rampage (significant trade-up for minions, but often a dead card)
Slam (since either you kill the minion and get no card draw, or you need another card to finish the job)
Shield Slam (too situational)
Whirlwind (does the same damage to your board)