So it's been a long time since I've read Goblin Slayer, but this just feels like food for Schera Zade. Schera's use of deflection to wear down her opponent's stamina, along with her ridiculously heavy weapon, would win in a straight engagement, no problem. She also has longer reach.
Her enhanced senses would render ambushes and guerilla warfare meaningless. See feats:
Throwing sickles with deadly accuracy at hidden crossbowmen in the middle of the night while in the midst of solo combat against a large number of combatants.
If GS chooses to engage with Bow & Arrow, I imagine Schera would return a sickle much faster, but I don't think she would use one until he tries to flee, otherwise.
I don't think GS has enough killing intent towards humans to activate Schera's Power Absorption, if it comes to that, and GS has high resistance to fear, so I imagine many of her mind manipulation powers wouldn't have enough of an effect.
The only thing I can see GS using to win here is his Gate Scroll, but Schera Zade is also a small target (smaller than GS, actually), and her horse increases her mobility. Though it might flood the area, I doubt it would actually be able to hit her since she practices use of mobility in battle.
Ah, I also forgot to put it on Schera's page, but she is capable of deflecting arrows and determining which ones would be fatal while they are in flight and being fired in quick succession for an extended period of time, though eventually she got hit in the armor of her shoulder. The arrow did not pierce her skin. Source:
The Girl Who Ate a Death God Episode 9: Grass is good sometimes
Voting for Schera Zade