Zeal wouldnt be recomanded as it would be a waste of at least 3 skill points and those skill points would really be worth it in Salvation, Resist Fire, Resist Cold or Resist Lightning. The level 1-18 is rather easy and you can use might aura level 1 to help yourself. If you think leveling isnt going fast enought you can use a merc. Most time the level 1-15~ are made in act 1 and doing some killing in act 2 with act 2 merc would make you hit 18 in no time. (give them weapon it make a big diff.)

Once you hit 18 you can use blessed hammer as it always been strong in low level and the only change it they now own at high level too.

Blessed hammer should be raised to raise to 10. There also should be 1 point in vigor as it can be very useful and add to blessed hammer dmg. After that focus on Concentration since it will help your blessed hammer dmg yes you will get about 1-2 dmg less then if you puted point directly in blessed hammer !
But the point is that the mana cost wont raise and it will help your merc/party making it much more useful.