Grant permissions under what authority?

I needed to grant my windows login on SQL Server 2005 UNSAFE ASSEMBLY permission, which I was able to do with a simple grant statement, but under what authority am I granting that permission to myself?  Is it the server owner or admin, being a member of administrators on the host, my machine?

Members of the sysadmin role can grant ANY permissions on ANY databases.  Members of the db_owner and db_securityadmin roles can grant permissions on ANY statement or object in THEIR database.  Object owners can grant permissions objects that they own, nothing more.

The account you are logged in as must have GRANT permissions or must use the AS clause to grant access as a different role.

For more info, take a look at:  GRANT Database Permissions

I was able to grant the permission as my login was under BUILTIN\Administrators, from my admin login on my machine.

By default, all members of the windows BUILTIN\Administrators group are members of the sysadmin role.

sysadmin