What work have you got to do? Big areas are best using a strimmer with a 4 stroke engine cow-horn handles and a harness. Also a visor and some ear defenders should be used.
From my experience of grounds maintenance…some years ago admittedly a fixed blade is only good if you are clearing a wide area of long grass and things like brambles etc and you are pretty sure you don’t have to ‘tidy up’ around any fixed objects. Also you can get plastic and metal blades, the metal ones can be quite dangerous if you don’t have experience of using them. The plastic ones will at least shatter if you hit a rock.
But like I said it all depends on what you have to do. Is it a one off?(hire one) or on going Maintenance?