Speed Graphics were used as handheld cameras for many years. They are designed so that you can get a much firmer grip on them than you can with most cameras. That is especially true if you keep the flash tube on the camera and use the solenoid shutter release. You will probable get a much sharper image at 1/100 that way than at 1/250 with a usual camera. That said, a tripod is the way to go if you possibly can.
Remember too, that many news guys when hand holding used flash. The effective shutter speed for exposure was therefore the burn time of the flashbulb. Much faster than the shutter.
Also the Flash light source is contrastier and so gives the appearance of additional sharpness.
While working on the deck as an LSE ( Landing Signalman Enlisted ), about to conduct Vert Rep ( Vertical Replenishment ), I watched with suspicion as a PC ( Plane Captain ) haphazardly used a can of ACC ( Aircraft Cleaning Compound ) near the HSDD ( High Speed Divergent Duct ) of an F-14 ( Fighter number 14 ). About 30 minutes later, the pilots fired up that engine and I heard a "Braaaang!" and saw a puff of smoke.
The can of ACC ( Aircraft Cleaning Compound ) had rolled into the HSDD ( High Speed Divergent Duct ) and then went down the intake, bouncing off of the IGV's ( Inlet Guide Vanes ) and not causing any damage to the TF-30's ( Turbofan 30 ) 16 compressor stages, a borescope procedure revealed….It was a 3 pass FOD ( Foreign Object Damage ) walk though, delayed my op.
Without reading through all the entries because the internet is quite slow today, I'm just going to quickly throw in my two cents and leave, but also apologize if I repeated something someone said.
I've used a graflex handheld myself. Mine has a body trigger, so I hold onto that side with one hand, and put my other hand on the bottom of the focusing rail holder, with my thumb and forefinger on the one focus knob. I find that a hand below the camera entirely helps support the weight better than both hands on the side.
If you have a flash unit of the newer style, attaching that securely can give a good hold on the camera.
Now, if you attach a side flash and a solenoid, you have a more comfortable grip and you can push the button on the flash to fire the shutter, you don't even need bulbs.