This may seem like a silly question, but I play so many board games, and i've seen this wording go both ways, so you may understand why this gets confusing for me.

When it says INT 2 or higher, are we talking higher on the initiative list being INT 1 & 2?

Or higher in Number being INT 2, 3, 4, 5?

Razorwings cause units with initiative 2,3,4,5 to route. Basically, the purpose of their ability is to "stun" the units that move later to prevent them from taking a turn at all.