Regardless of the temperature, Gallium is a poor choice for a sword.
Decoding its properties from Nex Terren's comment link:
Some of Gallium's mechanical properties:
Tensile Strength - How strong is it, or how much force does it take to pull it until it breaks:
15-40 MPa (compare to polyethylene [AKA plastic] 12-43 vs steel 500-2000)
Hardness - If you poke or scratch it does it deform:
50 on the Vickers scale (most hardness comparisons start at 80, it's a pretty soft solid - easily deforms or scratchs)
Young's Modulus - how easy is it to deform:
9.6-10 GPa (Most comparable to wood 11, again easily deformable. Most metals are 100+ steel is around 200)
Poisson's Ratio A measure of how much it deforms, ranging from 0 to 0.5:
0.47 (Most hard metals are much lower 0.2-0.3, it's similar to saturated clay 0.40–0.49, or Gold 0.42–0.44.)
Your sword would be solid but would easily bend if put under stress and would likely break if swung or used to block. I don't think it would be likely to shatter (it's not hard enough), it would just bend and break more like a plastic or gold sword than a glass sword.
Beyond its general weakness, I'm not even sure if you could sharpen it using any traditional means (it would likely melt from friction heat at the edge if you tried a whetstone). You could cast it into a blunt pointed/edged shape, but I'm not sure it would be worth it, as any minor handling would quickly bend or blunt it.