Here's the sharpener.

https://www.amazon.com/Fiskars-Knife-Sharpener-Black-78616984J/dp/B0000950Q4/ref=pd_aw_sim_86_1/146-9333338-7584415?_encoding=UTF8&pd_rd_i=B0000950Q4&pd_rd_r=f8d44bb8-8593-11e9-9baa-1f33018cf24e&pd_rd_w=Uy792&pd_rd_wg=ETqtH&pf_rd_p=469620d9-3e90-496d-9dc8-b19f900ba5fe&pf_rd_r=MKW28KEF80W1206Z5DJ2&psc=1&refRID=MKW28KEF80W1206Z5DJ2

I've never had a split come hit me in the nads, but sometimes they do fly and once or twice (in over a decade of splitting wood) I've bruised my shins. I always wear eye protection from small splinters. Steel toe boots are also a good idea just in case you miss the log in your seeing, I have a buddy that split his big toe in half splitting firewood.

Since you're to this, when using a splitting ax you want to take aim about 3-5" from the edges of the logs. These won't split large logs down the middle like a heavy maul will so instead you work at it from the outside in.