Good question, cyberguy. I was going to put that in the review and forgot.
In cases where the Bible writer is quoting from the OT, then we know he means God not Jesus. In this scripture there is no cross-reference given after the word Lord.
It is apparent to me that Paul meant Jesus if we look at the context of Ephesians 6:10.
In verses 7 and 8 we see that the WTS has inserted Jehovah although they are not direct quotes from the OT. Their reasoning is found in Appendix 1D of the large NWT.Rbi8 pp. 1564-1565 1D The Divine Name in the Christian Greek Scriptures
To know where the divine name was replaced by the Greek words Κ
ύ ριος and Θε ό ς, we have determined where the inspired Christian writers have quoted verses, passages and expressions from the Hebrew Scriptures
and then we have referred back to the Hebrew text to ascertain whether the divine name appears there. In this way we determined the identity to give Ky´ri·os
and the personality with which to clothe them.
Because the WTS has done that in verses 7 and 8, it implies that verse 10 must mean "Jehovah." But there are many cases where Lord is used in a passage yet not meaning that Jesus was meant in both, or God was meant in both.
But in verse 10, even the WTS is not bold enough to put Jehovah. But they have implied it by putting Jehovah in verses 7 and 8.
I don't agree with the WTS tactics. The WTS tries so hard to eliminate Jesus from their doctrine. It is as if Jesus is only an impersonal hammer that God uses. That is why they took the name Jehovah's Witnesses rather than something that indicates they are Christ's followers. Amazingly enough, for several years after 1935, the "anointed" JWs did not think that the "great multitude" were JWs. Only those who were spiritual Israelites could take that name. Even the administration thought that. Until 1938 the GM/GC were not even invited to the memorial or before 1935 were not even required to get baptized.