de can introduce an adversative ‘but’, yet so often it merely continues the expression. the addition of ‘but’ would have to be conditioned by the nature of the preceding statement. there is nothing in the greek to necessitate a ‘both’, but the rather epigrammatic nature of the phrase might want to be rendered by uniting the two adjectives with ‘both..and’.
Let all those that seek thee rejoice and be glad in thee: and let such as love thy salvation say continually, Let God be magnified. 5 But I am poor and needy: make haste unto me, O God: thou art my help and my deliverer; O LORD, make no tarrying.
In the context it makes sense to use de rather than kai due to the contrast with God. However, would there be signifigant change in meaning if the author were to use kai?
And should a “kai… kai” construction be normally translated “both…and” or “and…and”
“de” is here used only to stress the person using his following statement, one may not translate literately. A good translation could be “I am” for “Egw de”, even if “de” has nothing to do with “to be”. My try for an translation would be “I am poor and full of needs”.
I would say it could be read a couple of ways. And the fact that it is Septuagint Greek marks it quite differently from later Koine Greek (i.e. the New Testament). LXX Greek in many was was the bridge to gap Classical and N.T. Greek. My 4th year prof was always keen on completely ignoring δε when we came upon it in Classical settings. He was of the opinion that it was mainly used for punctuation (much like a period…i.e. a new sentence starts here) and could be left out when we were translating. He would probably prefer just “I am poor and needy” as a translation.
On the other hand…it seems pretty clear to me that in the context of the passage the δε is acting like a signpost, drawing a contrast to the previous statement. What the Psalmist is saying is, “Those that seek you rejoice k.t.l., but HEY…what about me God?” Therefore, I would be most tempted to tranlate it as “But I am poor and needy”.