A psychic has one main tool: his or her own consciousness. That tool can also be used as a weapon.
It is not very laudable to have the goal to intentionally harm others, but sometimes whatever goal you have set for yourself might resulting in unintentionally harming others. Just as a surgical knife can be a tool of healing or harming (even though both involve the destructive act of cutting), the mind and consciousness of a psychic can also be used as a psychic weapon.
The brute force way to use your psychic weapon is to overload and 'fry' the consciousness of another person, resulting in mental/emotional collapse and brokenness. (This too can be an act of healing - a psychic reset.)
The more common and subtle approach in using consciousness as a psychic weapon is to target the subliminal parts of the target's consciousness. (Subliminal consciousness is the narrow band of the subconscious which is just below the conscious.) This results in easy manipulation, something like involuntary hypnosis where the reality of the person is in part painted by the psychic.
To focus and enforce desirable patterns of psychic energies, there can be many psychic weapons of consciousness if you apply your imagination.