I am with you Hatch, the blood fuller on a sword, or knife, is a farce as for letting blood out, easier to pull out, etc. The flesh is going to close around the blade, or shaft. You may get some external bleeding, but not enough to be useful for trailing etc. . If the blade is pulled out, or the shaft, passes, through, or is pulled out in one way or another you will get blood, for trailing etc. As for grooves letting blood out, if it worked, it would ok for trailing, if there was not a pass through, but I doubt there would be enough for that. But as for swords, knives, etc. It doesn't matter if there is blood coming out, as it is for certain, filling up inside.
Bleeding out or in, is irrelevant. Bleed enough, and it is fatal.
I am on the "lightening" side for grooving blades, as for arrows, it had to have some significance wether it had anything to to with "Mojo" for the arrow, or helping to reduce warping, or a combination thereof, I have no idea, but it took extra time to do, and the arrow was a time consuming project for the native people with primitive tools. So if someone wants to put grooves on his arrow shafts, I have no problem with that. Sort of like spitting on your fish hook.
Wayne