Apparently you can buy a Kevlar reinforced "combat" umbrella, for a lot of money.
French president Sarkozy apparently used one against his citizens' thrown objects.
https://metro.co.uk/2011/03/31/nicolas-sarkozy-uses-armour-plated-umbrella-647785/https://www.core77.com/posts/24315/Battling-the-Elements-Umbrella-Innovation-Part-2I always thought it was the British who were big on umbrellas.
When I get into bad precip (Interstate), I lean far forward using only my right throttle hand on the bars, and rest my chin on my left fist with elbow on the tank, positioning my eyes just barely over (and right behind) the fairing/shield slipstream. When the helmet visor and/or glasses get too fouled, I flex up into the wind to blow it off, then get back down again. Then I power through whatever the precip gives me, looking for something to park under. Or just putting the miles in on the freeway. If I just sit back comfortably, I am blinded in no time (and a lot wetter).
Never seen much hail, and none golf ball size.
My back road over to the local Geo Washington Parkway (nice local ride) takes me right next to a big golf driving range. And if there's a big crowd of guys smacking off the Ts, I always get down low behind the shield for incoming slices. Stuff happens, and I have way too much money in my dental work as it is.