If YOU is the same ?person? throughout, then we know that they:
-Treated the speaker as a fairy tale.
-Made a joke about them.
-Tarnished their name with 'slander, mockery, and slur'.
-Had 'designs' revealed to them by one of:
--The speaker's instructions ('I charge you to...')
--The speaker's ward ('He is in my charge')
--The speaker's actions in battle ('CHAAARGE!')
---Which also revealed 'Secret words' to others.
--'Designs' could mean pictures or plans.
No thoughts on who yet, because my only thought was Gandalf.
hS