After playing the beta many times I discovered, while I was playing as the Torch Bearer, that some abilities do increase in energy costs as they gain levels. After doing a quick glance at the rest of the demigods, I found that this holds true for most abilities.
After doing some number crunching (to figure why I couldn't use some of my "Rain of Ice" as often as I used to), I learned that some abilities can increase in energy demands very quickly. This increase in energy demands can occur fast enough that you would have much difficulty in trying to use them (atleast until you the gain levels, and equipment to compensate). To put things into perspective, the power "Rain of Ice" at level 1 costs 310 energy to use, and a level 1 Torch Bearer with his 1550 energy can expect to use it 5 times before he needs to recharge. At level 5, a Torch Bearer can learn "Rain of Ice" level 3 which costs 930 energy, a large enough increase to deplete the Torch Bearer's 2182 energy after being cast 2 times.
Given how easy it is to nerf your character in this regard, I was thinking that maybe it would be worth while to allow you to open your skill tree and allow you to use the weaker setting (lower level version) until you get the energy you need to use the power at its highest setting. Maybe we could right click the power, and a shining light will circle that ability to indicate what version we are using. Regardless, I'm sure its within the power of the Torch Bearer (or other like demigod) to blast a couple of minions without wasting the energy needed to devastate an army.
P.S. Since I'm on the subject of selecting weaker versions of abilities, I'll bring up selecting alternate versions of abilities. Some abilities such as the "Explosive Mine" for Regulus (angel sniper) I find difficult to use. It seems to deal too little damage, has a small area of effect, and is set off by the first enemy to walk over it instead of having a 1 second delay so a couple more enemies might run into the AOE before it goes off. Being able to adjust some settings of the mines for instance would help to provide some flexibility in some of the powers we might encounter and use in this game.