I am all for making things real for haunts. The more realistic the more terrifying. I would suggest using a real beat-up bat or wooden club. Yes, real. But the nails should be fake. At first I thought you could make the nails real too but only on one side giving patrons something to briefly touch and then the other side make the nails foam. This idea is way too dangerous and I advise using your best judgment. But, my actual answer here is to use a real bat and make foam nails.
How? pick up a can of Great Stuff Foam. Lay down some wax paper and and just spray out the foam in nail or pointed spike shapes. When they dry, paint them to resemble rusty nails. Then just glue them to the bat.
I hope this helps but be careful with this last idea, that great stuff foam breaks if you drop the bat.