Totally awesome idea. Broadsword, katana, or scimitar handled umbrellas from Fight the Rain.
Rain: Ninja. You are but a mere mortal and no match for my powerful torrent. Do you surrender?
Ninja: Ah, Rain. You are a most worthy opponent and teacher. But I will never surrender.
Rain: Ha! Ha! Ha! Your bravery humors me. Please continue.
Ninja: Laugh now, Rain, for it will be the last time. (Unsheathes umbrella.)
Rain: The ninja umbrella. But I thought it was a myth!
Ninja: Used by the samurais before me. Passed down by my ancestors. Full of the wisdom of the ancients. With this umbrella, I will defeat you once and for all, and I will bring honor to my family and dry clothes to my home. HIIIIYAAAA!
Via Uncommon Goods.