Strengthen Death Duration?

[EQChaid]

Level 29 Shadow Knight only pet buff spell, Strengthen Death.
I was wondering if a GM might be able to answer the question about how long this spell actually lasts? The reason I ask is because the wiki has two different duration descriptions which are grossly different. 4-7 minutes or 1 hour!

"Fills your pet with rage, giving it increased attack speed, armor class, and strength for 1 hour."

"Duration 3.9 minutes @L29 to 7.5 minutes @L65"

This is important to know, because if it is 4 - 7 minutes, then it is going to take up a permanent spell gem to keep pet buffed. It takes a very long time to memorize this spell, so removing it and re-memorizing it every few minutes is not feasible.

Appreciate your time and response.