Assuming you are dealing with 2D LINE entities only, this could work
(defun c:bendl (/ h l ss i en ed p10 p11)
(or gv_offset (setq gv_offset 1))
(initget 6)
(setq h (getdist (strcat "\nOffset Distance <" (rtos gv_offset 2 2) ">: ")))
(or h (setq h gv_offset))
(setq gv_offset h)
(or gv_length (setq gv_length 1))
(initget 6)
(setq l (getdist (strcat "\nLength Distance <" (rtos gv_length 2 2) ">: ")))
(or l (setq l gv_length))
(setq gv_length l)
(while (setq ss (ssget (list (cons 0 "LINE"))))
(setq i 0)
(while (setq en (ssname ss i))
(setq ed (entget en)
p10 (cdr (assoc 10 ed))
p11 (cdr (assoc 11 ed)))
(entmake (list (cons 0 "LINE")
(assoc 8 ed)
(cons 62 1)
(cons 10 (polar p10 (angle p10 p11) h))
(cons 11 (polar p10 (angle p10 p11) (+ h l)))))
(entmake (list (cons 0 "LINE")
(cons 62 1)
(cons 10 (polar p11 (angle p11 p10) h))
(cons 11 (polar p11 (angle p11 p10) (+ h l)))))
(setq i (1+ i))))
(prin1))
-David