Hi Minh, unfortunately this is very crude work on the Saya and most likely something cooked up recently and unrelated to the Tsuka. Note how the mouth of the Saya has no Kurikata and is uneven? The Tsuba looks to be a modern casting of poor quality. There are vast quantities of assembled items like this being passed off as original Koshirae from Japan, dealers buy this stuff by weight and offload it on ebay. Don't feel too disheartened, many of us bought similar things early on without realising we were swindled.
All I can suggest is looking closely at high quality Koshirae, and investing in some good reference books that show what quality original Koshirae should look like.