Dive doesn't have any fancy mechanics, it's just "double attack now, halve it afterward". So, what you did with Blessing and Dive is technically proper, even though unwanted.
A Pegasus, when you Dive it, becomes 6 attack, and as such it does 3 hits. 6, 3, 3. Or so. Probably. I don't know, really. But someone tried, I'll try to find this.