Re: eth colossus sword
Assuming its ilevel is 41 or over, it will get anywhere from one to five sockets, with five having double the liklihood of any other number.
Edit: I now realize you were asking about a colossus sword. Such an item doesn't exist. The answer I gave above was for a colossal sword, which does exist. If you meant to ask about a colossus BLADE, then the answer is anywhere from one to six, with each number being equally likely.