ARM assembly - Addition of specific bytes from word-size values
LDR and LDRH are instructions for loading a register from memory. You are using R1 as a pointer to memory location 0x0B54A361. R10 then gets loaded with the contents of this memory location (which could be anything, but probably 0 if that particular memory location is not being used). 

To move (copy) data from one register to another you should use the MOV instruction. You can combine the move with other operations by using instructions such as AND or ADD, because the destination register can be different from the source registers. You may also be able to apply a shift or rotate with the same instruction.