另外我的版本是原版1.69.8109，无prc

有

我记得是有的，这个特技对所有偷袭都有效。刺客的招数只是换了个名字，本质上还是偷袭。

As of patch 1.66, a bug prevents this feat from working for an assassin who does not have sneak attack or sneak attack, blackguard. The improved sneak attack feats are still selectable for the assassin, but they will add nothing. If the assassin has even one die of sneak attack damage from rogue, blackguard levels, or item property then improved sneak attack works as expected.

我去nwnwiki上翻了下，貌似从1.66开始就存在该问题了？精通偷袭对夺命攻击无加成

https://nwn.fandom.com/wiki/Improved_sneak_attack

有加成啊，as of是在这个版本，意思只有这个版本有bug,不是在这之后都是的意思。

用测试模组对比测试了下，在只有刺客等级的情况下似乎真没效果

测试一下看看