The quote from the novel is:
令狐沖手臂微感酸麻
i.e. All he felt was a slight numbness - although that is an impressive feat when using a needle to block a sword, it isn't going to hinder LHC any.
There was also this quote:
當日在黑木崖上圍攻東方不敗,他手中只持一枚繡花針,可是四大高手竟然無法與之相抗,此刻細想 ,並非由於東方不敗內功奇高,也不是由於招數極巧,只是他行動如電,攻守進退,全然出於對手意料之外。
The reason that the four couldn't defeat DFBB was not because his internal power was incredibly high (though it may well be), nor was it because his techniques were extremely sophisticated (though they may well be), but because he came and went like lightning, and his advances/retreats were completely unpredictable by his opponents.
It has been repeatedly shown in this particular novel that inner power matters little in a sword-fight - LWC has repeatedly triumphed (or in the case of RWX, matched) over opponents with much superior inner power to his own. This is because in high-level fights, the weapons don't clash at all, so there is no opportunity to use inner power to overwhelm your opponent.