You're doing fine with the sword. Might want to swap Dajarte for Grapagos, since having negative magic resistance% hurts.
As for the armor you can up it, or if you're rich enough get Ultimi reup instead.
Monty Cerberus is fine for now, but you might want to consider Raton for obvious reasons.
Myrica slot is pricey so I guess ns is alright for now.
Focus on getting your Dex to at least 300: that's the point where Issen doesn't get any skill delay reduction anymore.
Then get both your Vit and Agi as high as possible, as it increases your attack and allows for better survivability.
Make sure to have at least -3 seconds skill delay with 300 dex, so you can spam Issen without any problems.
With Izu II and Monty you can accomplish this by using Cheltil for example.
There's no real need to restat, just stop adding Str for now and focus on your three main stats. You can add Str later on again.
Good luck! Nice to see some special sword Samurai around here ^~^