The Collaborative International Dictionary of English v.0.48:

Ruthful \Ruth"ful\, a.
   Full of ruth; as:
   (a) Pitiful; tender.
   (b) Full of sorrow; woeful.
   (c) Causing sorrow. --Shak. -- Ruth"ful*ly, adv.
       [1913 Webster]

WordNet (r) 3.0 (2006):

ruthful
    adj 1: feeling or expressing pain or sorrow for sins or offenses
           [syn: contrite, remorseful, rueful, ruthful]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "ruthful":
   afflicted, bleeding, charitable, clement, commiserative,
   compassionate, condolent, doleful, dolorous, forbearant, gentle,
   human, humane, lenient, melting, merciful, miserable, pitying,
   rueful, soft, softhearted, sorrowful, sympathetic, sympathizing,
   tender, tenderhearted, understanding, warmhearted, wretched