[Fern]

Probably more of an oversight, but you can overwrite a Rampage LV with a weaker one, and it even acts a little bit weird. For example:
 
Hit a target with a 40 Power Rampage weapon twice, you get LV20 Rampage.
 
But if you hit that target again with a 24 Power Rampage weapon afterwards, then it will be LV12 Rampage instead. The duration will also be made 2 rounds once again.