I think that might be difficult insofar as different talents etc. might have various strengths of effect on abilities (say the Pyromaniac talent is a 10% damage increase, and some other new talent improves the duration of skills like firefly etc.).
As a result of this, it should probably just be revealed when hovering over the skill increase what it will do. Say you hover over fire magic and it says "Each rank of Fire Magic increases damage by 5%, duration by 5%, and decreases AP cost by 5% rounded down" or something similar.
This way, we can know generally when trying to add points what we will be getting, and it allows different talents to have different magnitudes and not stick us into a strict scaling of all fire magic talents simply adding ranks to fire magic, etc.
In other words, we get both clear information on improvements and the availability for variation in how improvements are made.
Just my thoughts on the matter, criticisms or thoughts welcome.
