I would omit "and obligation." and write "It is my most pleasant duty to thank." That way it's still flowery, but has only one element, rather than two. You could translate it with both, but it sounds like overkill. (As does talking about oneself, as "the author," in the third person - unless one is a poet: "Not long ago, the author of these lines, / In the mad pride of intellectuality / Proclaimed the power of words...")