Hey @Rader,
You can just run this mutation
<user1> <mark> <movie1> (weight=0.5) .
It would set the weight of that edge to 0.5. In other terms, this new value would be SET over the last value (i.e. replace).
Unless you meant, all the edges for the predicate mark have the same weight; and you want to change all of their weights in one go. That’s not currently possible. You’ll have to specify the edge to assign a weight to it. You could, however, represent it differently by having one edge dedicated for the weight. For e.g., <weight> <mark> "0.5" .