It doesn't matter in the way I used her in the video. Abilities only run so the gun doesn't matter. What matters is that it has magazine and fire rate mods with sharp precision shot on it. If you're going for a mobbing build, Secret Garden is currently the best choice, good overall gun with a passive that buffs Freyna's Abilities. if you're going for a bossing build, weapon doesn't particularly matter as long as it can slot in sharp precision shot or firing fiesta (personal preference).