Chinese Idiom puzzle 19 (中文填字遊戲)
Corrected according to Tang Ho's comment.

曹魏
洛神赋
刻不容缓
王重阳
刮骨
急流勇退
纸上谈兵
母凭子贵
计上心头
重于泰山
借力打力
刽子手
竭尽全力
亲力亲为
重蹈覆辙
柔情似水
历历在目
暗无天日
弥补
感人至深
匠人
明白
千载难逢
兴师问罪
时来运转
法家
万里长城

A. 母仪天下
B. 历久弥新
C. 子时
D. 魏王
E. 子欲养而亲不在
F. 匠心独运
G. 洛阳纸贵
H. 目中无人
I. 量力而行
J. 弃暗投明
K. 征兵
L. 白手兴家
M. 计穷力竭
N. 重见天日
O. 问斩
P. 刻骨铭心
Q. 全军覆没
R. 匹夫无罪
S. 千千万万
T. 缓急轻重
U. 柔软
V. 手下留情
W. 强人所难
X. 英勇
Y. 山不厌高，水不厌深
Some notes:

Not an idiom. It is a four-character word coined in a costume drama. (According to Tang Ho it is a common expression.)

E. The original text in 韩诗外传 should be 子欲养而亲不待也.
J. It means 'leave the reactionary camp and cross over to the side of progress'. Often used to describe someone leaves the enemy and joins (surrenders to) 'us' (from the narrator's point of view).
L. For me 白手起家 is more often heard. 白手兴家 seems to be Cantonese. Here it can only be 白手兴家, for in question 16 起师问罪 is used very seldom (it is even not in an idiom dictionary).
O. I think it should be understood as 'sentence to (问) capital penalty (斩)'.
T. 轻重缓急 is more often heard.
Y. Another version gives 海不厌深. Here it can only be 水不厌深 due to question 16.