in this first one, you see max energy increases lineraly with 125 energy per 20 focus, until you get to 1000 focus where the rate per 20 focus decreases slightly. maybe this will have a bigger impact when new gear that increases focus more comes out, but there's not much of a leveling off when it comes to energy. Now in this one you see how focus effects skill dmg of firebolt and ice shards at lvl 50, at 2 different magic abilities(with and without full dl). again still playing with numbers but made a graph to show the decline in dmg increase per focus. looks like at dmg wise you don't want to have more then 2000 focus, since it looks like that is where it will lvl off. also looks like ice magic has a bigger impact on ice dmg then fire magic has on fire dmg. 2) is there a perfect mage ? Edited this part out. Dont want the hypothetical idea to take away from the actual data. Thiis data collection was about when to stop increasing focus for fire or ice mage, so that you are not wasting them. Turns out that point is really hard to get to atm, but not impossible.
Here is some data for you guys to play with Have fun

P.s. I do realize that the title for a graph is supposed to be y axis title vs x, too lazy to fix now