As I said earlier in another thread:
Good engraving will usually improve a Good knife.
Good engraving will usually NOT improve a Bad knife.
I like well designed and executed engraving on knives as my collection would indicate.
As others, I feel a knife's design needs to stand on it's own merit without help of embellishments. Engraving/embellishments should be the icing on the cake so to speak.
Some "Art" knives/"ART" folder may be an exception to the above.
I believe engraving gives a maker the opportunity to demonstrate a very broad range of artistic talent from the laborious hammering or grinding of the steel to shape, to the very tedious and detailed task of engraving fine images into the steel.
Many knives will benefit aesthetically from the correct style and amount of engraving, however sometimes may not increase the overall value of the piece enough to recoup the cost of the engraving. This would be especially true of knives in lower priced ranges. On the other hand, many engraved knives will benefit aesthetically and will raise the value of the piece well over and above the cost of the engraving. In my opinion, engraving also highlights other detail or features of the knife. In some cases, engraving can be used to cover flaws or to add a little pizzazz to an otherwise plain piece. I have found that engraving adds a little durability as engraved areas of knives generally dont show scratches as much as polished or hand rubbed satin finished areas.
I always prefer knives to be engraved by the maker, with the exception of collaborations by maker/engraver partners such as Bob Loveless / the late Dan Wilkerson, D Alton Holder / Bruce Shaw, Edmond Davidson /Jere Davidson, Tom Overeynder and Brian Hochstrat and of course Harvey Dean and Steve Dunn. My favorite knifemaker/engravers are Jerry Fisk, and Steve Dunn. Its practically gotten to the point where these talented artists knives are almost expected to be engraved and values can suffer it not. My favorite engravers in no particular order are Joe Mason, Barry Lee Hands, Jere Davidson, Brian Hochstrat, Antonio Montejano and Francesco Amatori, Bruce Shaw, Simon Lytton, Julie Warenski, Ray Cover Jr. and Ron Skaggs.
Seems as of late, knife engraving is gaining popularity and quite a few well known and talented firearm engravers are taking interest in knives. I've heard reasons for this, however won't get into it here.