劲敌的英文：
a foe worthy of sb.'s steel
an enemy worthy of sb.'s steel

参考例句：

On April 9, Kuwait has marginally beaten qatar in basketball with a score of 97:93 and won this year's championship.
在9日进行的球类项目比赛中，科威特篮球队以97:93的微弱优势战胜劲敌卡塔尔队，荣登本届西亚运动会篮球比赛的冠军宝座。

An enemy worthy of one's steel.
值得与之较量的劲敌.

How did you manage to massacre your strong opponent?
你是如何设法彻底击败劲敌的？

To grapple with an unexpectedly formidable opponent.
遇上劲敌与一名出乎意料难对付的对手拼搏

foe是什么意思：
n. 敌人；反对者

A cornered animal is a dangerous foe
穷寇莫追

The drone is the foe of us all.
懒惰者是我们所有人的仇敌。

With power and to spare we must pursue the tottering foe
宜将剩勇追穷寇。

worthy是什么意思：
adj. 值得的；有价值的；配得上的；可敬的

You are accusing a worthy falsely.
你是在厚诬君子。

The laborer is worthy of his hire.
做工的人应得其报酬。

He is a worthy man.
他是个可敬的人。

steel是什么意思：
n. 钢铁；钢制品；坚固
adj. 钢制的；钢铁业的；坚强的
v. 钢化；使冷酷

Good adhesion to steel, galvanized steel and aluminum alloy.
对钢铁、锌钢材及铝合金有良好的附着力。

Steel and gasoline are industrial products.
钢和汽油是工业产品。

The towers are surfaced with steel plates.
在塔面上加了一层钢板。