I actually own a warhammer, a cold steel warhammer. The spike isn't significantly more metal than the hammer. It's actually about equal, because you want it to be balanced, it's also actually quite light. It may sound cool to try and swing a 20lb sledge around in combat, but in reality you will just end up tired and dead very quickly.
In any event I would be inclined to allow you to take the -4 improvised weapon penalty to use it as a bludgeoning weapon. However, you could also just carry around a cudgel/club with you. They're free, so you can carry around as many as you have available carrying capacity.
I have issues with style and just lugging around all sorts of weapons. It looks tacky having a pick, a sword, and a club hanging off you. If what you say is true about your IRL hammer/pick thing, I really wish they made a proper stat block for the hammer/pick with a "B or P" damage type. Sure, we can just go with a morningstar, but... it's just not as sexy as the hammer/pick.
If you want a weapon that deals all types of damage try a monks spade or grow a bite.
The manly approach is to power through the DR: Just do loads of damage.
Adventurer and his lacky
fought zombies, oh so nasty
with no sword in hand
both were completely slammed
but at least they were not tacky
- Twin tombstones on a lonely road
I have issues with style and just lugging around all sorts of weapons. It looks tacky having a pick, a sword, and a club hanging off you.
I mean, I'm just suggesting you carry around a club. Not carry around a tree worth of clubs. Check out Valeros, he's got sword, dagger, and a bow on him.
In any event, in a level or two you wont see any more enemies with DR bludgeoning/slashing/piercing anymore so it wont be a major concern for long.