I presumed this about the size of A. major. ie rather smaller than A. athada.
The forewing have spot 9 (uppermost) of the band shifted inwards.
Spot 6 on the hindwing is wider at the top.
It should be Arhopala sublustris.
There is some variation in the shape of spot 6.
Others in the alea subgroup of the cleander group(recorded in Singapore) can be eliminated thus.
Spot 6 quadrate A. phanda. A. normani (submg. & postdiscal band on hindwing always close.)
Forewing termen rounded, spot 6 almost triangular, A. aroa.
A. milleri probably impossible to separate except looking at the upper.
However in valid examples forewing spot 9 not shifted in.
TL Seow