Go away, give the 20 k plat to a needy froglok cleric named Courtin Andidride of Mt server so he can buy a mount and a ft item.
However if you insist on spending the money you will want...
Haste item. Best you can buy.
2hs and 2hb and piercing weapon.
I would start out with a weighty polearm, centi warspear, and the shovel from lake rathe (its free!) All the weapons are cheap and you wont have a lot left after spending over 10k for a good haste item.
Rallic back, bag of sewn evil eyes for your loot.
Ldon armor, Gothic steel, cauldron steel, etc, good armor that will take you into your 30's at least.
Spend the most on a haste item, that way if you dont like the melee type and bag the character you can get most of your money back in resale.
But really Courtin does need a horse, he looks so small and lonely, and Ms. Mousey is pining away for him to get his horse and pay a visit.