Well, that's difficult to estimate. The first person she killed (if you don't count those S9 victims that died as collateral when she was spotting for Sundancer) was Coil. Afterwards was the fight against Echidna, where she killed a bunch of clones, but the personhood of Echidna's creations is dubious. She was the one who made Sundancer burn Echidna and a few people she still kept captive, so those could be added to the total. Next came the Butcher (does that one count as one person or fourteen people?

) Afterwards Director Tagg and Alexandria. Then came the timeskip. We have no idea how many she killed during that time, but as she was focused on recruting villains instead of killing them, it won't be many. S9 clones that died at Weaver's hand onscreen: five. Aster. Do we count the Yangban and Elite the Endbringers killed after Taylor's Group won their cooperation? No, I don't think so. Mantellum, maybe others of the Irregulars. And then came Khepri, who threw Capes at Scion, some of them giving out under her control. From rereading, her army is smaller than memory insists, and her fatalities are fewer too. I think it adds up to dozens or hundreds.