Note the sharpened beard in the photo. If you need to hook, adding another wound is part of the stroke. The comment about the spike being easily extracted also has significance, some utility hawks aren't sharpened or meant for it - they add ridges for grip when levering.
At about this stage some extras not shown above become options, like a top spike, or a few others that resemble medieval designs. What isn't mentioned is that the handle should be oval, not rounded, with possibly some element to let you know it's orientation - which way the bit is facing. Hawks get their impact from being light with a longer handle than a hatchet. They use speed, not weight.
It should go without saying that practice and training would be needed. The overhead strike of the spike hawk implies pulling it back toward you, and self inflicted knots on the skull from inadvertent impact could be a distraction at the wrong time. It happens as any of us begin to be familiar with a new tool. We cut ourself with knives, bang our shins with axes and mauls, or reach a bit too far back with a hammer overhead rather than to the side. It's just as important with hand tools as it is with weapons, however, weapons tend to inflict much more serious wounds.
Surfing the web for video, most demonstrations aren't at combat speed nor use a "live" blade precisely because of it, and for darned good reason. All that isn't necessarily directed at the OP, we all need a reminder. I just started using a hawk and it's not like a hammer, hatchet, or an axe - there is a difference why it's a hawk and there are different motions in using it.