Talk:Starlight Glimmer/@comment-10390252-20170530100952

A Proposal:

Starlight isn't necessarily more powerful than Twilight; rather, she is better at creating and modifying spells. Her shield spells and attack spells, just as an example, are simply more energy-efficient and manifest in more effective ways.

I suspect that this is her True Talent: Spell-crafting. It's certainly strongly implied in both The Cutie Map - Part 1, The Cutie Re-Mark - Part 1 and Every Little Thing She Does that she is excellent at either creating spells or modifying existing ones for far more powerful and efficient effects.