The Collaborative International Dictionary of English v.0.48:

Devoutful \De*vout"ful\, a.
   1. Full of devotion. [R.]
      [1913 Webster]

   2. Sacred. [R.]
      [1913 Webster]

            To take her from austerer check of parents,
            To make her his by most devoutful rights. --Marston.
      [1913 Webster]