When I said "It works for me, anyway (only tried a crossbow since that patch).", what I meant was that it works for me, and that I had tried with a crossbow since the patch. Sorry I was so vague about that. I quicksaved, attacked a couple monsters, got the listed damage, quickloaded, put 5 points in Piercing and got the additional piercing damage. The damage was on the low end for the stated 19-39 bonus range, possibly because I was at the end of an act, and jumped to the battlefields to test this, where the monster level was lower than my own.