The person is a blackmailer.
A person who blackmails others is typically referred to as an extortionist.
A blackmailer is a person who blackmails another person - who uses money or other resources to bribe or someone to do something.
can you call someone a welth of knowledge
a person
A person?
You call that person a scholar.
You would call them someone who peruses.
You can call someone who does not lie honest, truthful, trustworthy, or sincere.
an ally
someone who works for a business
You can call someone who is wise and has good sense as a sage or a wise person.
If someone tries to make you feel jealous.You must call that person a despo or a looser and a jerky person.