It looks to be "Mutual Recognition" certainly not Reciprocity. Also known as an informal agreement.
From the VSP site - Listing of states with which Virginia has mutual recognition (Jurisdictions have informally agreed to honor permits issued by the other):
Delaware is in the list
From the DE site - . However, as of today Delaware does not recognize the concealed deadly weapon licenses or permits issued by states other than those listed below, and these states do not recognize Delaware's concealed deadly weapons licenses as valid.
Virginia is in the list
Now, what is the difference between reciprocity and mutual recognition? Maybe with mutual recognition you're not "as protected" legally, being out-of-state. I'm not trying to read more into this than is necessary.