The goal of this weapon is to give engineer a full on utility secondary, that provides little kill potential on its own, but allows for a range of different uses on many scenarios.
You can pull enemies toward you for clean combos with your shotgun, prevent enemies from fleeing or bring enemies who are trying to play safe right to your sentries range.
The ability to displace enemies would feel specially annoying to heavy, which can't really move himself around as easily to dodge. So I opted to make so that engineer is moved towards him instead, which can be both used to engineer or heavies advantage. A Unique interaction that should make this specific encounter more bearable to deal with.
The ability to pull yourself towards buildings and grab ammo from afar allows engineer to both place his buildings in previously less accessible places and to play more offensive with the ability to use his buildings as an escape plan.
I thought about the possibility of this being a melee option as well, but with so many upsides, I wouldn't be able to think about how to balance it without removing much of his engineering potential, which would feel counter intuitive. This could also be a primary option to provide a gameplay style in which the engineer relies more on his secondary, but right now I don't think there is a secondary powerful enough to justify a replacement of a primary to make it work. But both options are not totally out of question.
I also thought about the possibility to grab allies to take them out of sticky situations and allow the engineer another way to support his team, but this could very easily be used for trolling as the player would have no time to decide if they want to be dragged or not.