We had a short discussion of arrows and arrowheads in my last game session. This occasioned some thoughts and comments I figured I'd share.
Blunts: These obviously are "war blunts," since they don't have a penalty to damage or a armor multiplier. A tipless blunt is just a wooden arrow, and those have a bunch of problems. They're half cost, but that's probably because you don't need to put a point or an edge on them.
If you do want no-tip arrows, or you convert an arrrow into a blunt by removing the tip, I'd treat these as cheap wooden weapons, with -1 Acc, -5 to both ranges, and a (0.5) armor divisor.
Cutting arrows: These things do serious cut damage. How serious? A ST 13 composite bow does 1d+3 cutting damage with them. Min/Av/Max is 4/6.5/9. A minimum damage hit on an unarmored HP 10 man will cripple his arm or leg. A roughly average damage hit - let's say 7, because you can't roll 6.5 - would almost do enough to automatically dismember the arm or leg, and 8 or 9 will dismember. Youch. And ST 13 composite bows aren't exactly lofty weapons of legend, either - a ST 11 man with Strongbow 2 can draw one. Bows in my DF game are more usually in the ST 15-19 range, and crossbows even heavier.
So these are clearly not dinky little moon-shaped arrowheads for cutting banners off of poles, but a thrown blade powered by a bow.
One suggestion my players came up with was an armor divisor of (0.5). That would make them still arm-lopping on unarmed foes but quickly drop off the effectiveness scale against more armored foes. Makes sense - who pulls out the crescent arrow or Y- or U- shaped arrowhead to punch through plate or mail or an o-yoroi? Of course, that might seem pretty unfair when you look at any other cutting attack versus armor.
Can they target vitals? Seems like you could aim for the heart with them, but is it going to be as easy to penetrate as with a broadhead? One option here is to say yes, but it changes the injury multiplier from x1.5 to x2, much like cutting the neck does. Only unlike the neck, it's rare for the vitals to be less armored. I wouldn't allow an eye strike except on a very large subject simply because the orbital bone of a skull is well-designed to stop broad-area attacks from entering the brain. Of course, you could just say "no, vitals is x3 injury" but then there is no good reason to use impaling arrows - they're marginally better against the torso but worse against limbs, no better against the neck, etc.
Still, the problem remains - this is pretty much a niche arrowhead, but in game terms, it's making up for a lot of the weakness of the better missile weapons (bows, crossbows), especially versus supernatural foes or solid objects.
One further way to deal with this is reduced damage. They can simply not hit as hard, thanks to the arrowhead's shape, less ability to focus force, etc. The way to do this is give them -1 or -2 damage. Even with -2 that ST 13 composite bow will do 1d+1 (2/4.5/7) and still have some solid effects, but they're toned down. 2/3 of the time an unarmored man will have a crippled limb, but can't get dismembered by the arrows until a ST 15 or 17 bow shows up and rolls well.
I'm not sure if I'll do this - it really depends on how my players feel about it. But I am at least considering the damage reduction overall, but allowing an improved injury multiplier for the vitals.