Frenzy is currently inconsistent in terms of activating in which I think it is a gimmick perk or very bugged
Tested it in most environments
When constantly dealing damage to enemies it activates ~15 seconds
When just receiving damage and not doing any ~35 seconds
When not doing ether surrounded by enemies it doesn't activate
When not in combat the perk is lost ~5 seconds when no enemies are around for you to kill.
Bungie this perk needs an update to be more reliable, in the current state its not worth having.
For a change make it gained when dealing or receiving damage after a short period of time like 10 seconds then lost after 10 if not in combat with a timer going down from the last damage done or received.