I don't know exactly what OP is saying should be the case but arming time should be ~ 1.5s
MS is a factor but there is clearly no trap with less than 1s trigger time after impact.
*Zoom in on these to see the debuff visual timer*
Clearly more than 1.5s to me. If anything trap arming time does vary depending on different factors. But it is not a flat nr like 1.0 for sure.
https://youtu.be/0rWJwMwbRnY?t=620