Does increasing the nock weight really stiffen the spine of an arrow if point weight is unchanged?
any weight added to the nock end does incresas dynamic spine, don't know if it's a one to one ratio or what
Technically yes but it may not be enough for you to notice.The further your balance point is forward,the more influence your nock weight has.
I saw some weights for carbon arrows that are designed to add 50 gns to the nock end-I'm a wood guy so no idea how well it works.