[quote=@Flamelord]
<Snipped quote by Sublimation>

Even in canon, though those Masters who try it tend to have hax magics or special abilities that let them survive more than five seconds. 
[/quote]

Your overestimating servants here. Rin with her special jewels can kill almost any servant with a surprise attack, they are A ranked attacks by the way which are lethal to a servant body.

Kuzuki, albeit with reinforcement, is capable of defeating Saber, of course he has trained in an assassination school for almost all his life. Emiya naturally can have a defensive fight against a servant with projection. Emiya Shiro without any knowledge of his abilities managed to live more than "5 seconds" against Lancer, albeit with Lancer not being serious. A half rate reinforcement poster can block a light thrust with Gae Bolg. Etc.

Oh by the way, Kotomine Kirei using command seals can fight servants. Hint hint.