You might experience an issue with missing or malformed Unlink and PDF toolbar tools with version 2016.3.914 of Kendo UI Editor.
The issue could be observed on the following demos:
and is also logged with Medium severity here.
Here is how the PDF icon looks when the problem happens:
A possible partial workaround is to add the following to the page styles:
Note that the solution works for all themes except the Office365.