Need a bit more info. Were you parsing swarm pets or your main pet? Burnout XIII has a higher hit damage modifier than Arcane Distillect, The former has a 24% modifier at Rank I and a 25% modifier at Ranks II and III. Arcane Distillect is only a 15% modifier, and the highest one takes priority (they are not additive). Swarm pets have no hit damage modifiers. As such, they benefit notably from Arcane Distillect. Because of how pet damage is calculated (hit damage modifiers multiply the DI portion of hit, but not the DB portion), you won't see a full 15% increase in damage. It should still be noticeable, although 10 minute parses probably aren't ideal.