The handlers you are referring are related to images and documents where we use sflb extension for Content Items. You can check whether you cave the following handler
| <add name="SitefinityTemplate" path="*.template" verb="*" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" resourceType="Unspecified" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32"/>
although you are not supposed to register it manually.
the Telerik team