अन्वयः

यत् that arrow, अमितात्मना god of wealth, कुबेरेण by Kubera, स्वयम् himself, स्वप्ने to him in dream, दत्तम् gifted, सेन्रन्दैः, सुरासुरैरपि even for suras and Asuras, दुर्जयम् difficult to win, दुर्विषह्यं च or to resist

M N Dutt

Seeing that mighty shaft set by him (on the bow-string), the highly powerful Laksmana, possessed of dreadful prowess, (in his turn) took up another arrow, bestowed by Kuvera himself of imme jurable soul in a dream, unconquerable, and incapable of being borne even by the celestials and Asuras with Indra at their head.

Summary

That arrow was gifted to Lakshmana in dream by Kubera, the god of wealth and even Suras or Asuras cannot resist it and is difficult to win.

पदच्छेदः

कुबेरेण	कुबेर (३.१)
स्वयं	स्वयम् (अव्ययः)
स्वप्ने	स्वप्न (७.१)
यद्	यद् (१.१)
दत्तम्	दत्त (√दा + क्त, १.१)
अमितात्मना	अमित–आत्मन् (३.१)
दुर्जयं	दुर्जय (१.१)
दुर्विषह्यं	दुर्विषह्य (१.१)
च	च (अव्ययः)
सेन्द्रैर्	स (अव्ययः)–इन्द्र (३.३)
अपि	अपि (अव्ययः)
सुरासुरैः	सुर–असुर (३.३)

छन्दः

अनुष्टुप् [८]

छन्दोविश्लेषणम्

१	२	३	४	५	६	७	८
कु	बे	रे	ण	स्व	यं	स्व	प्ने
य	द्द	त्त	म	मि	ता	त्म	ना
दु	र्ज	यं	दु	र्वि	ष	ह्यं	च
से	न्द्रै	र	पि	सु	रा	सु	रैः