Mandates Issue

So Mandate of Borrowholm gives +100% reputation gain for their faction.
I am Honored and have 12000+ reputation level with them - should I be honored so I can buy the Mandate ?

It says I dont have enough reputation to buy it, but if I have to be honored at their faction, that means max level reputation, so what would that be good for after gaining max level ?

The only bonus I see is to give it to another char ? But doesnt that mean they shouldhave a specific amount of reputation at specific factions to use the mandates ?

Revered is the max reputation level.
At Honored, you can buy a writ, which means your char gets +50% reputation with them.
For Mandate, you need Revered level, meaning maxing it out. Your assumption is correct, it’s good for giving to other characters. They can use a mandate as soon as they have access to a shared stash, no reputation required.