There are two ‘subjects’ that have influenced the study of the period 1792-1815, for both good or ill: historical revisionism and hagiography. Unfortunately, both have been used, or more accurately, misused when discussing the period in general and Napoleon in particular. The following comments on historical revisionism are taken from historyplex.com/historical-revisionism-influence-history and hopefully can shed some light on what historical revisionism actually is and how it affects the study of history.
Definition of historical revisionism: ‘Critical reexamination of historical facts with or without new evidence. Historical revisionism pertains to the act of altering historical facts for benevolent or malevolent reasons.’
‘Revisionism describes the process of critically reviewing established theories and suggesting amendments. It comes into play when newer findings contradict older theories, or when a mistake is discovered in the previously held explanations during reexamination. Revisionism is important for maintaining the accuracy of human knowledge.’
‘The study of history is a part of social and natural sciences. In it, facts and information about the past are gathered through various means, such as studying old documents, analyzing ancient artifacts, etc. Through this information, historical theories are formed.’
‘Like any other scientific theory, historical theories too are subject to change when newer facts and information emerges which contradicts them in part or whole. Historical revisionism is the practice of reexamining historical theories.’
‘The following are the cases when historical revisionism is useful.
1) When through research, new historical data and evidence surfaces, the current theories and conclusions must to be reassessed to verify their validity. 2) When governments disclose previously banned documents or information to the public. 3) When ancient languages are deciphered, which makes it possible to study ancient writings in greater detail. 4) New scientific technologies and instruments help in better analysis of the ages and authenticity of old artifacts. 5) When cultural changes make it possible to examine historical events with a new perspective.’
‘Historical revisionism allows past events to be reviewed in an objective and non-biased manner. This is usually done by academicians and historians who are eager to learn the actual chain of events from the past. With the help of authentic documents, proven facts, and other supportive pieces of evidence, they are able to critically examine historical theories.’
‘Once enough evidence on specific histories has been gathered, respective amendments are suggested, and are put up for review by recognized historians and other authorities. If these changes are approved, they become part of the accepted history, and are no longer considered to revisionists.’
‘However, with all the benefits of historical revisionism, there is also the chance of it being abused. Sly politicians, deceitful historians, or other such shady personalities may possibly make deliberate attempts to distort or rewrite history in order to stir up a conspiracy or wrongfully obtain some benefit out of it. This the reason why the practice of revisionism and revisionist theories are often viewed in a bad light.’
‘Most modern-day revisionist historians do legitimate work. However, just as other branches of science have to deal with pseudosciences, historians too have to deal with illegitimate historical revisionists theories.’
‘Thus, the practice of revisionism can have both, a good as well as a bad influence on history. Revising history in an objective way is beneficial in learning the actual truth. This type of revision in history, supported by concrete evidences and facts, is known as legitimate historical revisionism. However, if the revisionist theory is based on loose facts or non-existent evidences, then it is known as illegitimate historical revisionism, which can lead to distortion history, lead people astray, and also cause a number of social and political issues.’
Definition of Hagiography: (From Webster's Dictionary).
1: biography of saints or venerated persons.
2: idealizing or idolizing biography.
Hagiography for the Napoleonic period is usually employed as an accusation against an author or a work when it is a sympathetic work towards a historic personality. A case in point is Vincent Cronin’s excellent biography of Napoleon, which is sympathetic to Napoleon. The accusation of hagiography is usually leveled at the book by those who characterize Napoleon in a negative light. Cronin’s work does not fit the above definition.
That ‘attitude’ is ahistorical and usually inaccurate, and with that inaccuracy the subject then tends to gravitate to bad and inaccurate revisionism as explained above.

I have come across a couple of videos on Youtube, where key issues are discussed rationally. The first is about the (ab)use of the term "revisionist" by a WW2 guy, who explains that it is a historian's job to revise history https://www.youtube.com/watch?v=ruqt8uv__18 The second is about the development of the philosophy of history, looking at how ideas develop to produce objectivity, although it does conclude that objective history is what is "agreed upon" (now who said that?!). https://www.youtube.com/watch?v=FVm3eNMmCMY