Forfend is used in contexts relating to some kind of real or pretended danger or other unpleasantness. In humorous and ironic use, forfend typically appears in the phrase “heaven forfend,” and, like “heaven forbid,” expresses a usually ironic desire that something not happen or be done. In general use, if you forfend something unwanted or undesirable, you ward it off or prevent it; and if you forfend yourself from or against something, you protect or preserve yourself from it.
to fend off, avert, or prevent
to defend, secure, or protect
to protect (to keep from harm, attack, or injury) [v FORFENDED, FORFENDING, FORFENDS]