As stated by others, I find Toby to not be weak at all.
His basic attack is arguably one of the strongest basic attacks in the game after acquiring the Me 'N My Magnets which is a straight 25% boost of power on his shots when they pass through his barrier projection.
His Arc Mines are also very powerful utility tools when properly upgraded. I personally take Sorry I Broke Your Legs, Plasma Mine, and What’s Mine is Yours. This causes them in order of the stated upgrades to Slow enemies damage by them, deal 50% more damage to shields, and increases the range of their Electric field. With those upgrades, you slow enemies to a crawl and practically dismantle their shields instantly when they get caught in the field of electricity emitted by the mine. Its no wonder why they deter people so well.
His barrier is also amazing for not only upping the damage on his Railgun, when taking Me 'N My Magnets, but for also being a protective wall which allows Toby to snipe and harass people with out being retaliated on unless they break his forcefield.
The only thing bad on Toby is his ultimate which honestly feels like the worst ultimate in the game. As things stand right now, I find his railgun to provide more power and dps than his ultimate does. Which is really funny considering his ultimate has a lengthy cooldown while his Railgun does not.
But if Toby’s ultimate was to get buffed, then he would probably need to be nerfed on either his Railgun or Arc Mines.