What I'd like to say happens is it goes by whatever % of the stat you put in.

For example, my relic, I went with the ratio of 100% Determination (31 pts), 70% Skill Speed (31 pts), and 30% Crit (13 points), and my Nexus is now 32 Determination (100%), 32 Skill Speed (70%), and 13 Crit (30%), which falls in line with that. Should be more obvious once the item level goes up more.