The phrase "saw at" generally means to cut or chop repeatedly with a sawing motion. However, there are several synonyms for this phrase that can be used to make your writing more interesting. Some options include "hack away," "slice through," "chop relentlessly," "carve persistently," "separate with a saw," "saw systematically," "cut vigorously," "divide continuously," and "section deliberately." Depending on the context of your writing, some of these synonyms may be more fitting than others. By using a variety of synonyms, your writing can become more descriptive and engaging.