Sgian Dubh
>Paul, I suppose optimal would be to have a knife with a bevel on one face only,perhaps a two ended knife as in the link you provided. Still, this bird beak pattern has worked well for me for many years. Yes, a slight tilt is used to get the point into the corner and the cutting edge tight against the face of the tail or pin.

As to sharpening, I think it might have been sharpened two, three or four times since I made my knife some time in the 80's. Only the tip needs to be reasonably sharp, so it's not an onerous sharpening task. If the tip is too sharp the sliced line in the end grain is hard to see, so a very slight rounding of the tip works well. I suppose it produces an awl like scratch rather than a knife line.

In the end it's just another way of transferring a mark. As long as it works I guess that's all that matters. Slainte.