Becky, in the school system where I taught, any play weapon of any kind meant an automatic suspension. You and your child would have to appear before the school board to be re-instated.
We did have a kindergarten child expelled for this. The reason I know is that the information was in his permanent record when I taught him in 5th grade.
With the school shootings today, there is almost universally a zero tolerance policy. I realize this is only a toy, but to some it might not appear as a toy and could cause a major panic. We had students bring many things to school that should never have left home that were immediately seized and never returned. I was surprised when it was handled at our school level sometimes and not reported to a higher authority.