
FantheFlames |
Warpriests automatically get their sacred weapon bonus with the deity's favored weapon. The way to get any other weapon to have the sacred bonus is to take the Weapon Focus for that specific weapon.
SRD wrote:
In addition to the favored weapon of his deity, the warpriest can designate a weapon as a sacred weapon by selecting that weapon with the Weapon Focus feat; if he has multiple Weapon Focus feats, this ability applies to all of them.
So it's actually possible to have two weapons getting sacred weapon bonus at first level. Your deity's favored weapon, and the weapon you take the free Weapon Focus in.

Melkiador |

Many warpriests have 2 sacred weapons anyway. You get the favored weapon of your deity and the weapon you chose to have weapon focus in. And it seems to be rare to want the sacred weapon of your deity, since Sacred Weapon Damage is so weird about favoring strange weapons with low base damage but lots of other properties.