I really need you to realize that if Steve doesn't want Slap to get close, he can completely shut him out. Steve's effective range for regular attacks is 4 meters, and that drastically increases to 5+ depending on the weapon. This is not including ranged weapons like bows. It's essentially telekinesis. This also goes for
block placement, which Steve can use to have complete battlefield control and stop Slap from ever coming close to touching him. The second Steve sees even one of Slap's abilities, he will abuse his elytra and firewords and completely stomp Slap with the spear and mace.
Slap has no way to stop himself from getting blown up by tnt minecarts or end crystals. He has no way to consistently deal damage due to having far less range. He has no way to keep up with Steve's kit in combat due to his swapping between gloves taking much longer than Steve. He has no way to deal with getting burned by
lava bucket spam. He has no way to deal with Steve's nigh-infinite resurrection. He has no way to deal with getting filled with arrows with a wide variety of enchantments and status debuffs.