The AT-ST has Arsenal 2, which says that each mini in a unit can use up to 2 of it's weapons. General Weiss also grants Arsenal 2. From what I've read, this means each Arsenal stacks, giving an ATST Arsenal 4, effectively meaning it can use all of its weapons.
Units can also split fire for each uniquely named weapon it has.
So does this mean that, if possible, the ATST can shoot up to 4 units in a single attack?