Weakness of mind, together with misstatement, even if not amounting to technical fraud,1 such as a representation by a third person acting in collusion with the grantee that her brother would buy the property taken in exchange at a great advance;2 or a false statement that a life estate was reserved to grantor's wife in the deed;3 or a false statement of the value of property;4 or circumstances of oppression, even if not amounting to technical duress,5 as where a helpless and bed-ridden grantor is threatened by grantee with desertion;6 or the combination of misrepresentation and circumstances of oppression,7 may be sufficient to establish the fact of undue influence.