User blog comment:Miskos3/Episode 272: Fairy Tail Zerø: The One Who Teaches Magic, Review/@comment-4933386-20160221022412/@comment-4829046-20160221074946

I think it's the topic of combat. Geoffrey was used to constantly battling mage guilds on every other day and it was an attack on his home turf. He just analyzed the situation and observed the environment. Zeref on the other hand was completely passive and was rather alarmed since he thought he might take more innocent life and likely never faced a moment in his life where gentle forest creatures approached him en masse in a friendly manner. It isn't a matter of power here but situation.