Hi, for gawein you need some servant. Strong st Archer , and good np gain if possible.
If you want, you can go an level up a euryale, she is a incredible 3 star Archer with anti male np and lot of stalling. She can destroy gawein.
But if you don’t want to level up a servant pretty much only for that fight (she is still good, but she shine vs male saber so), you can go for Chloe /archuria/Orion in your friend list .
If you are into it you can even solo him with a support Chloe or cu alter (I have done both, and I am pretty sure archuria can do it to, but I did not try her).
If you want I can add you, and you can use either my archuria or my cu alter (I removed Chloe from the support list).